Fisheries

Abstract

Management of reef fish populations requires insight in their resilience to anthropogenic stressors. Studies on temporal variations in reef fish populations and their abundance responses to environmental changes are crucial to the development of ecosystem-based management.  Nineteen years of voluntary fish survey data of reef fish at the west coast of Bonaire Marine Park (Caribbean) were analysed to investigate the effect of environmental changes on local reef fish populations. Various anthropogenic stressors that influence the coral reefs of Bonaire were studied in recent years. This study studies to what extent these stressors and protective management measures can be related to the observed population trends. In addition, reef fish population responses to specific events were analysed. In general fluctuations in sighting frequencies were species-specific and difficult to interpret.  Although some noise in the data couldn’t be filtered out they show an overall negative trend in sighting frequencies in the 155 studied species.. A comparison of the average frequencies between the first five years of this study with the last five years resulted in an over 10% decrease in 64 of the species, while 30 species increased over 10%.  Three large parrotfish species decreased by approximately 50% over time and there were indications of a slight negative trend in mid-sized parrotfish as well. In fishery targets, the most intensive fished group, large to mid-sized groupers, decreased strongly. After the abundance of these groupers decreased to near zero, two species belonging to other fish families started to show signs of sequential overfishing.  It is unclear if larval import will compensate for the loss in reproductive capacity of the species in decline. Recent literature on recruitment distances suggest that the level of larval import is low on isolated islands like Bonaire, resulting in dependence of self recruitement.  Another event with strong effect on population dynamics are the mass mortality events in moray eels. Especially in two Enchelycore species these resulted in sigmoid like trends. The 2008 and 2022 mass mortality events were first noted at the onset of a period of sea water warming, paralleling various reef fish species in the Red Sea. This gives further support to the hypothesis that the current increase in warming events will lead to more frequent mass mortalities.  f.p.bennema@gmail.com 

This report aims to assess historical fisheries in the Caribbean Netherlands since the first inhabitants started exploiting the sea around them. In doing so, WWF-The Netherlands seeks to understand how fisheries and fishing traditions have influenced the marine ecosystem in the past, and hence what this ecosystem may have looked like before the start of marine resource exploitation. We hope that this will provide a more realistic view of the variations and impacts on baseline perspectives, and thus more effective targets to aim for in policies and plans for the future.

The purpose of this report is to update recent catch trends in the Saba Bank fisheries with the data from 2016 and 2017.

For the lobster fishery (Panulirus argus), the number of fishing trips (and number of traps set) gradually grew from 2012 to 2015 but has since levelled off. The resulting landings of lobster have shown a similar pattern of increase up to 2015 but have now levelled off at around 70 tonnes annually. Increasing landings per unit effort indicate that the formerly reduced lobster abundance, which had been declining since 2000 and which had reached its lowest level in 2011, has subsequently increased relatively steadily all through 2017, and now has increased back to levels close to those of 2007. The average size of lobsters taken, continues to be large, which is favourable to gradual stock recovery.

Mixed landings of reef fish in the lobster fishery have fluctuated between 10 and 20 tonnes annually. The LPUE abundance index in bycatch species also shows a decrease of about 35% from high levels in 2000 and 2007 to lowest levels in 2011, followed by an increase up to 2013, after which landings have levelled off.

In the redfish trap fishery (Lutjanus spp.), the number of trips in the redfish trap fisheries had grown significantly during the period 2012 to 2015. In 2016 effort increased again to 625 trips. In 2017 the exerted fishing effort dropped down to about 350 trips, a level seen last in 2012. The landings of redfish have fluctuated over this period, with lower values in 2012 and 2017 and higher values in 2014 and 2016. The LPUE abundance index shows a decrease by 50% between 2007 and 2011, followed by an increase to slightly higher and constant values between 2012 and 2016, while in 2017 the LPUE abundance index continued increasing. The only snapper for which sufficient data was available, was the silk snapper, Lutjanus vivanus. Average size of the silk snappers landed continued its increasing trend, indicative of gradual stock recovery. The drop in snapper landings, despite the higher LPUE in 2017, can especially be ascribed to the 6-month closed season implemented that year (Graaf et al. 2017).

The overall conclusion is that for, both the lobster and redfish stocks, stock status, based on the LPUE index, and size-structure trends have continued in developing favourably. Bottom drop longline, pelagic and bycatch landings have remained much less important and have shown no significant new developments.

There are two matters of concern that require follow up. Firstly, the positive prognosis for the snapper “stock” status may partly be based on targeting geographically different stocks as well as different species. Hence the data as collected and analysed may actually be presenting a too optimistic assessment. To evaluate whether this is actually the case will require more detailed analysis based on individual species, as well as more accurate geographical recording of catches than as currently practiced. The second matter of concern regards the fate of the traps that were in the water on the Bank when the hurricanes Irma and Maria struck the area in September 2017. If trap loss was large, this may lead to higher detrimental impacts of ghost fishing in the coming years.

Dutch below

Queen conch are facing immense pressure leading to a dramatic decrease in their populations.  Luckily, a new project, started at the Curacao Sea Aquarium in 2020, will explore ways to reduce mortality rates and develop new methods for effective restocking of natural populations with hatchery-reared conch. 

Photo credit: Julia Ehrenheim

The large marine gastropod queen conch (Strombus gigas) is a charismatic and iconic symbol of nature and one of the most important demersal fishery resources in the Caribbean region. Trade of the species (largely for consumption) is regulated by the CITES treaty, to which the Kingdom of the Netherlands is party. 

The Problem

Today, these iconic marine snails are threatened by over-exploitation and loss of shallow water habitats, throughout the Caribbean as well as in the ABC islands.  Human activities have led to degradation of nearshore conch habitats causing breeding failure, decreased growth and survival of juvenile conch. Excessively low densities mean that animals of breeding age fail to find mates and therefore also fail to breed (the so-called Allee Effect). Queen conch are also particularly vulnerable to overfishing due to their unique life history (pelagic phase, density-dependent survival and reproduction). The exploitation of queen conch throughout large parts of its natural range has led to population collapses and decrease in population densities to levels where mating success is diminished.

Photo credit: Julia Ehrenheim

Hope on the Horizon

In 2020 the Queen Conch Hatchery Project was started at the Curacao Sea Aquarium with Julia Ehrenheim as the key scientist. The science of hatchery production has been well established for many years but rewilding to bolster natural populations has consistently failed. Therefore, the main goal of this project is to find ways to reduce and/or eliminate high mortality rates that occur in early life stages and develop methods for effective restocking of natural populations with hatchery-reared juvenile conch. In order to find answers to various elusive questions, Julia has started the research that she will use for her PhD degree at the University of Wageningen under Professors Tinka Murk and Dolfi Debrot.

The Experiments

Her first experiments aim to address the movement behavior of juvenile conch. For this she and her students tracked the activity of juvenile conch in a controlled hatchery environment. The results show that juvenile conch are more active at sunset than in the early morning or during midday. They also appear to preferentially move towards the current. Such experiments need to be done in the field but already suggest ways to facilitate the relocation of released hatchery conch and that juvenile conch will be most vulnerable to predators at sunset.

Photo credit: Julia Ehrenheim

A second experiment showed that juvenile conch often aggregate together in the wild. Therefore, she studied if there was a beneficial density for growth. The first finding showed that juvenile conch grew the most in shell length with a density of 200 conch per m2. Lower and higher population densities gave lower growth rates and lower total shell length, even though all were grown under the same conditions of food availability.

Correlations between weight and growth (in total length) indicate that there are distinct phases of growth. It seems that growth alternates between predominant growth in the thickness of the shell and in total shell length. Both do not occur simultaneously. The significance of this phenomenon to juvenile survival is not understood.

Implications

These findings for hatchery-reared conch will be further investigated and verified in wild grown juvenile conch. Taken together the results of this PhD project will help clarify why juvenile hatchery-released conch are so vulnerable and what needs to be done to enhance their survival so that they can be effectively used to restore natural populations.

Photo credit: Julia Ehrenheim

DCNA  

The Dutch Caribbean Nature Alliance (DCNA) supports science communication and outreach in the Dutch Caribbean region by making nature related scientific information more widely available through amongst others the Dutch Caribbean Biodiversity Database, DCNA’s news platform BioNews and the press. This article contains the results from several scientific studies but the studies themselves are not DCNA studies. No rights can be derived from the content. DCNA is not liable for the content and the in(direct) impacts resulting from publishing this article. 

Kroonslakken staan onder enorme druk, wat leidt tot een dramatische afname van hun populaties. Gelukkig is er in 2020 een nieuw project gestart in het Curaçao Sea Aquarium, waarin manieren worden onderzocht om de sterftecijfers te verlagen en nieuwe methoden te ontwikkelen voor het effectief uitzetten van natuurlijke populaties met in kwekerij gekweekte kroonslakken.

Foto: Julia Ehrenheim

De kroonslak (Strombus gigas) is een charismatisch en iconisch symbool van de natuur en een van de belangrijkste demersale visbestanden in het Caribisch gebied. De handel in de soort (grotendeels voor consumptie) wordt gereguleerd door het CITES-verdrag, waarbij het Koninkrijk der Nederlanden partij is.

Het probleem

Tegenwoordig worden deze iconische zeeslakken bedreigd door overexploitatie en verlies van ondiepe leefgebieden, zowel in het Caribisch gebied als op de ABC-eilanden. Menselijke activiteiten hebben geleid tot achteruitgang van leefgebieden van kroonslakken aan de kust, waardoor het voortplanten mislukt en de groei en overlevingskans van jonge kroonslakken afneemt. Te lage dichtheden zorgen ervoor dat dieren op geslachtsrijpe leeftijd geen partner vinden en dus ook niet voortplanten (het zogenaamde Allee-effect). Kroonslakken zijn ook bijzonder kwetsbaar voor overbevissing vanwege hun unieke levensloop (pelagische fase, dichtheidsafhankelijke overleving en voortplanting). De exploitatie van de kroonslak in grote delen van zijn natuurlijke verspreidingsgebied heeft geleid tot het instorten van de populatie en het afnemen van de populatiedichtheden tot niveaus waarop het paringssucces is verminderd.

Foto: Julia Ehrenheim

Hoop aan de horizon

In 2020 werd het Queen Conch Hatchery Project gestart in het Curaçao Sea Aquarium met Julia Ehrenheim als belangrijkste wetenschapper. De wetenschap van de productie van kweekerijen is al vele jaren goed ingeburgerd, maar het opnieuw verwilderen om natuurlijke populaties te versterken, is consequent mislukt. Daarom is het belangrijkste doel van dit project om manieren te vinden om de hoge sterftecijfers die zich in de vroege levensfasen voordoen te verminderen en/of uit te bannen, en om methoden te ontwikkelen voor het effectief uitzetten van natuurlijke populaties met in kwekerij gekweekte jonge kroonslakken. Om antwoorden te vinden op verschillende moeilijke vragen, is Julia het onderzoek gestart dat ze zal gebruiken voor haar promotieonderzoek aan de Universiteit van Wageningen onder professoren Tinka Murk en Dolfi Debrot.

De experimenten

Foto: Julia Ehrenheim

Haar eerste experimenten zijn gericht op het bewegingsgedrag van jonge kroonslakken. Hiervoor volgden zij en haar studenten de activiteit van jonge kroonslakken in een gecontroleerde kwekerij omgeving. De resultaten laten zien dat jonge kroonslakken actiever zijn bij zonsondergang dan in de vroege ochtend of middag. Ze lijken ook bij voorkeur naar de stroming toe te bewegen. Dergelijke experimenten moeten in de natuur worden gedaan, maar suggereren al manieren om de verplaatsing van uitgezette kroonslakken te vergemakkelijken en dat jonge kroonslak het meest kwetsbaar zijn voor roofdieren bij zonsondergang.

Een tweede experiment toonde aan dat jonge kroonslakken in het wild vaak bij elkaar komen. Daarom onderzocht ze of er een gunstige dichtheid voor groei was. De eerste bevinding toonde aan dat jonge kroonslakken het meest groeiden in schelplengte met een dichtheid van 200 kroonslakken per m2. Lagere en hogere dichtheden zorgden voor lagere groeisnelheden en een lagere totale schaallengte, ook al werden ze allemaal gekweekt onder dezelfde omstandigheden van voedselbeschikbaarheid.

Correlaties tussen gewicht en groei (in totale lengte) geven aan dat er verschillende groeifasen zijn. Het lijkt erop dat de groei afwisselt tussen overheersende groei in de dikte van de schaal en in de totale lengte van de schaal. Beide komen niet gelijktijdig voor. De betekenis van dit fenomeen voor de overleving van jonge kroonslakken wordt nog niet begrepen.

Implicaties

Deze bevindingen voor in kwekerij gekweekte kroonslakken zullen verder worden onderzocht en geverifieerd bij in het wild geboren jonge kroonslakken. De resultaten van dit doctoraatsproject zullen helpen verduidelijken waarom jonge kroonslakken die in kwekerijen zijn uitgezet zo kwetsbaar zijn en wat er moet worden gedaan om hun overlevingskans te vergroten, zodat ze effectief kunnen worden gebruikt om natuurlijke populaties te herstellen.

Foto: Julia Ehrenheim

DCNA

De Dutch Caribbean Nature Alliance (DCNA) ondersteunt wetenschapscommunicatie en outreach in de Nederlandse Caribische regio door natuurgerelateerde wetenschappelijke informatie breder beschikbaar te maken via onder meer de Dutch Caribbean Biodiversity Database, DCNA’s nieuwsplatform BioNews en de pers. Dit artikel bevat de resultaten van verschillende wetenschappelijke onderzoeken, maar de onderzoeken zelf zijn geen DCNA-onderzoeken. Aan de inhoud kunnen geen rechten worden ontleend. DCNA is niet aansprakelijk voor de inhoud en de indirecte gevolgen die voortvloeien uit het publiceren van dit artikel.

Published in BioNews 64

Summary

Over the last 10 years, the Caribbean Netherlands fisheries on Saba and St. Eustatius have been monitored and multiple assessment reports have been made by Wageningen Marine Research (WMR) in collaboration with local Data Monitoring Officers (DMOs). However, due to challenges in collecting the necessary data, there are gaps in the data which can lead to large uncertainties in the current stock assessments and make it difficult to deliver a more detailed assessment of the fisheries and the state of the stocks.

The specific objectives of this report were to present the data challenges and provide recommendations to address the shortcomings in the current data collection. By addressing these and providing solutions, improvements of the Caribbean Netherlands fisheries monitoring program can be made.

The main gaps identified in the data are:

- Limited coverage by the logbook data, especially the case in St. Eustatius. This implies that large raising factors are applied when estimating total effort and landing estimates, which leads to more uncertain estimates.

- Landings not reported by species (at least for the main species) and port sampling for species composition not frequent enough to be able to produce landing estimates and abundance indices at the species level (instead of species groups). For instance in Saba, the number of trips sampled to estimate the length-composition of the landings was on average 60 per year (excluding 2011), with mainly lobster and redfish trips being sampled. On average, around 40 trips per year were sampled for species composition, taken representatively from the different fishing methods. This is less than one catch sampled per week. This is too low and needs to be intensified if data availability and quality are to improve.

- While some species are over-sampled for length-composition, others are not sampled enough to be able to compute reliable length-based indicators.

Our key recommendations are:

o Port sampling and biological data collection-frequency must be stepped up to meet minimum targets.

o Going along with fishers on the vessels, in order to measure catches on location. (Then fishermen won’t have to wait at the harbor for the DMOs work to be done.)

o Facilitate working in morning/midday/evening shifts. This enables data collection after regular working hours, e.g. when fishers come home late in the day (5-6pm).

o Set quantitative targets for data collection. We suggest targeting for a minimum of 70% logbook declarations, activity surveys, catch species composition and weight data (tonnes), while doubling the effort on selected species of importance

o Data collection will now need to include exact biometric data to establish length-weight and fecundity curves, sex ratios and reproductive seasons for individual species, as well as the collection of otoliths from a range of sizes for each species as a basis for age and growth studies by the WMR otolith lab.

o Have DMOs sit in a workspace with a clear view of the harbor where fishers arrive with their catches, so they can immediately act when boats arrive with their catches. This is mainly an issue for the St. Eustatius DMO.

o For bycatch measurements photographing the fish on a cm grid surface can save measuring time in port or on vessels. o Increase willingness of fishers to participate in data collection. o Incentivize fishers to participate by organizing regular (bimonthly or quarterly) gettogethers where the DMOs update fishers on some monitoring results, providing snacks and drinks.

o Provide dedicated freezer storage space for fishers at the harbor, enabling DMOs more time for the port sampling. Fishers willingness to wait for port sampling is understandably limited. By providing dedicated freezer storage facility, the DMOs can take extra time needed for sufficient biological sampling (i.e. species composition, length, sex) while the catch of the fishers stays fresh. The same can be done for lobster catches if a port-based holding area is provided. 

o Provide modern technologies to the fishers and/or DMOs, e.g. Electronic Reporting Systems (ERS) such as electronic logbooks, and GPS systems such as the Vessel Monitoring System (VMS).

o Arrange for closer involvement of WMR in work planning for the island DMO’s

Abstract The Bonaire Marine Biodiversity Expedition (2019) was organized by Naturalis Biodiversity Center in Leiden (the national museum of natural history of the Netherlands), ANEMOON Foundation (a Dutch organisation of marine ecological research involving citizen science), and STINAPA Bonaire National Parks Foundation. This field survey explored the marine biota of Bonaire, an island in the southern Caribbean. Species lists were produced of several groups of organisms, which include many new records for Bonaire and also some species new for science

Summary

Coral reefs are a vital part of Curaçao’s economy, providing revenue from ecotourism and fisheries, as well as providing shoreline protection. A vital coral species, Diploria strigosa, is a major reef-building species around the island, and contributes enormously to the health of the reefs, making it a prime candidate for this project. Physical oceanic processes, such as waves and currents, influence the health of these corals by introducing oxygen-rich water through mixing of the water column. In order to understand more about the growth and vitality of coral around Curaçao, it is therefore critical to understand how these processes influence the movement of oxygen around coral reefs.

This thesis set out to collect field data to investigate the existence of a relationship between hydrodynamics and dissolved oxygen near coral reefs around the island of Curaçao, as part of a larger project, the SEALINK project. SEALINK, part of the Dutch Research Council (NWO)’s Caribbean Research program, is an interdisciplinary research initiative to assess the impact of land-based and water-borne substances on the coral reefs of the Dutch Caribbean. Through a fieldwork campaign, dissolved oxygen concentration, wave data, and current velocity data was collected from seven study sites on the southern coast of Curaçao. Acoustic Doppler current profilers (AD2CP) and oxygen loggers were deployed through diving, and left on the seafloor to measure for six hours. A statistical analysis was run to test the validity of using current velocities as a predictor for dissolved oxygen values. Finally, a computational fluid dynamics (CFD) model was created using the fieldwork data in order to assist in the understanding of processes that influence dissolved oxygen around coral reefs. The results from fieldwork show that the extent of the relationship between waves, currents, and dissolved oxygen depends greatly on the location and tidal cycle. Study sites closer to the eastern point of the island showed that velocity and dissolved oxygen are connected, and that velocity has a greater capacity to predict dissolved oxygen values. The CFD model assists in a deeper comprehension of the influence of flow and other processes that can impact dissolved oxygen fluctuations around coral reefs.

EXECUTIVE SUMMARY

Fisheries on Bonaire, Saba and St. Eustatius (Caribbean Netherlands) are important for the local economy and food provision on the islands. In the Caribbean Netherlands, fisheries and (dive) tourism contribute significantly to the GDP, with 1% and >50% respectively. Whereas in the Netherlands, this is only 0,1% for fisheries and the fisheries industry (Agrimatie, 2020) and 4,4% for tourism (CBS, 2019).

Fisheries can have a negative impact on the health of a marine ecosystem. In the past, fishing activities have negatively affected the health of Caribbean coral reefs (de Graaf et al. 2015, de Graaf 2016 & de Graaf et al. 2017). The current impact of local fisheries in the Caribbean Netherlands on the marine ecosystem is largely unknown but is expected to be prevalent. Fisheries are regulated through outdated fisheries regulations (Ecovision, 2018). Fisheries monitoring on Saba and St. Eustatius is limited to the landings only. On Bonaire, no monitoring is being carried out. In addition, very limited information on fish stock health is available and no studies into the seafood market structure have been performed. For the Caribbean Netherlands, no reliable information is available on the import and export of seafood, seafood sales nor consumption statistics.

This market study was performed to analyze the local fisheries and seafood supply chain on Bonaire, Saba and St. Eustatius. The goal of this study is to provide recommendations to WWFNL to enhance sustainable practices in the fisheries and seafood supply chain in the Caribbean Netherlands through market mechanisms. A total of 361 interviews were performed and additional information was acquired by a literature study and consulting local stakeholders and authorities. Interviewees were subdivided into four groups: professional fishermen, supermarkets/ restaurants, consumers and importers/exporters. Interviews from the four categories were analyzed for each island separately.

On Bonaire, fishermen mainly catch pelagic species and they primary sell these to middlemen on the island. The vast majority of the restaurants on Bonaire serve locally sourced seafood (85%) while only few supermarkets sell local seafood (27%). Fishermen on Bonaire also indicated to fish on and/or source seafood, including conch and lobster, from Las Aves (Venezuela) indicating that not all ‘local fish’ is fished in the waters of Bonaire. Whether ‘local’ seafood sold on Bonaire originates from Las Aves or Bonaire itself is unknown and unmonitored, masking a potential shortage in local fish stocks. Fishermen on Saba mainly fish for lobster and redfish. Almost all lobster is exported to St. Maarten, part of which is shipped onwards to Hong Kong. Some fishermen also sell part of their catch to local restaurants and consumers. During this research, all restaurants on Saba said to serve local seafood, and 40% of the supermarkets sell local seafood. Fishermen on St. Eustatius primarily catch lobster and reef fish and indicated that they sell their catch to local consumers, restaurants or transport it to St. Barthelemy. However, according to the former data monitoring officer (DMO), a large part of the lobster catch is also exported to St. Maarten and St. Martin. This was not indicated by the interviewees. Of the interviewed restaurants 58% serve local fish and only 22% of the supermarkets sell local seafood on Saba.

We have found that, to stimulate sustainable practices, supermarkets and restaurants on Bonaire and Saba would consider promoting local sustainable species, boycott less sustainable species and/or would consider to implement an ecolabel. Boycotting less sustainable species is not a preferred option according to restaurants and supermarkets on St. Eustatius.

Consumers on Bonaire and St. Eustatius primarily buy local seafood directly from fishermen. However, during the interviews on Bonaire it became clear that many consumers are not aware that these fishermen are in fact middlemen. On Saba, consumers have no preference for buying local seafood at a certain location. Quality is indicated as the most important purchasing criterion, followed by origin (local vs non-local) and sustainability. Consumers indicated to be willing to pay more for sustainable species.

From this market study, it became clear that the seafood supply chains on Bonaire, Saba and St. Eustatius completely lack transparency. There are currently no central locations where consumers can buy local seafood. No information is available or provided on the species, origin and capture method.

On Bonaire, fixed prices of local seafood were implemented by the government in 1996 to ensure that local residents are able to buy locally sourced seafood (see Appendix 5). These fixed prices have not been revised since. Fishermen are still receiving the same price for their fish, whilst the costs of fishing and living have increased and catches have declined.

When trying to obtain information on the fisheries sector from local authorities, responsible agencies and/or international databases, it was found that structural, reliable and comprehensive data on import/export, number of fishermen, total landings and registered seafood selling locations is not available for Bonaire, Saba nor St. Eustatius. Because of this lack of information, we have not been able to draw quantitative conclusions from information gathered with the interviews. Therefore, we have not been able to give detailed recommendations on specific market mechanisms. However, we have formulated recommendations for qualitative improvements in the seafood sector in the Caribbean Netherlands. These recommendations are summarized below.

RECOMMENDATIONS

We recommend to implement a comprehensive fisheries management plan on Bonaire, Saba and St. Eustatius. This fisheries management plan must include a monitoring scheme in which at least the total landings per species, the bycatch levels, fishing gear, number of fishermen and fishing trips are monitored and registered for each island. With this information, together with fishery-independent data where required, fish stock assessments can be carried out which will provide insights into the effects of fishing activities on the fish stocks. This monitoring must be structural and will provide information to evaluate and adapt the management system when necessary. The fisheries management plan should also include mandatory fishermen registration, improved data collection on seafood trade flows, including the import and export of seafood and a traceability system.

In the past, both national and local fisheries regulations have been developed and implemented without participation of fishermen. This has resulted in unclarity about the responsibility of legislation as well as unfamiliarity with, lack of support for and non-compliance with the law. Fishermen, the local government and national park authorities should work together in updating and implementing marine park regulations when these affect or concern fisheries. This will increase involvement, understanding and compliance and will improve collaboration between these stakeholders.

We recommend to increase the visibility of the fisheries on the islands through a visibility and awareness campaign targeting consumers, restaurants and other seafood buyers and resellers. This will improve the ability of consumers to find and recognize local fish and make sustainable choices, as well as becoming aware of the impact and role these fisheries have on the islands. Awareness on sustainability in the fisheries sector should include advice on which species to choose or which to avoid. This visibility and awareness campaign will also be beneficial for the fisheries as this will enable them to position themselves as a sustainable, economically and culturally important actor on the islands. This will enhance their sense of responsibility and recognition on the island and hereby increase the incentive to follow regulations and collaborate with fisheries authorities.

Summary  

Saba is a tropical island in the Dutch Caribbean that is known for its unique ecosystems and rich biodiversity both above and below the waterline. Only 5 km from Saba lies the Saba Bank, the third largest atoll in the world and largest marine protected area of the Kingdom of the Netherlands. The rich biodiversity and abundance of marine species attracts tourists and fishermen to Saba and the Bank. Both fisheries and tourism are therefore of great socio-economic importance to Saba. However, both sectors have a direct impact on Saba’s ecosystems. For instance, in both the lobster and redfish trap fisheries, species are being overfished, with bycatch being an issue of concern. The Saba Conservation Foundation conserves and enhances the unique terrestrial and marine environment of Saba and therefore plays an important role in both sectors. 

A precautionary and adaptive management approach must be developed to halt the decline of the fisheries stocks. For this approach a mutual understanding and cooperation between stakeholders, in this case fishermen, residents and tourists, is required. A first step towards this understanding is to engage in a dialogue with them. Engaging with stakeholders is important to understand their knowledge and interests, interact more effectively with them and increase their support for given policies or programs, that may be executed by the Saba Conservation Foundation. Therefore, my internship aims to assess fishermen’s perceptions and the knowledge and attitudes of residents and tourists on and towards Saba’s fisheries.  

From a literature review and semi-structured interviews, I obtained fishermen’s perceptions on the current status of Saba’s fisheries. The perceptions of Saba’s residents and tourists on the current status of Saba’s fisheries were obtained through a questionnaire about seafood and sharks.  

Although my study was challenged by interview and questionnaire limitations, I found that fishermen have not really noticed a change in their fisheries stocks, despite the monitored decline. Furthermore, from fishermen’s perceptions it becomes clear that overfishing and bycatch are issues to be tackled, with the help of funding and/or assistance to improve the current status of Saba’s fisheries. I also found that residents and tourists know the most important commercially fished species on the Saba Bank and prefer and/or mostly eat those species as well. The most important reasons not to eat a certain type of seafood for both respondent groups relates to environmental concerns such as: endangered-, overfished- and/or protected species. Hence, residents and tourists know quite a lot about Saba’s fisheries and seem to act on that knowledge most of the time. Moreover, residents and tourists have a very high knowledge level on sharks and both a positive attitude towards them. Releasing sharks caught as bycatch is strongly preferred by both respondent groups.  

My internship shows that Saban fishermen are willing to solve the current issues of overfishing and bycatch and that residents and tourists want to see a sustainable fishery in which sharks are treated well. Therefore, it is important that fishermen, residents and tourists come together and collaborate to support sustainable fishing practices on Saba and the Saba Bank. 

This report is an update of earlier published reports on the status and trends in the of Saba Bank fisheries (Graaf et al. 2017, Brunel et al. 2018). The new analyses presented here are based on three additional years (2018-2020) of data collected by the Saba Bank Management Unit.

Lobster fishery

After a period of increase from 2012 to 2015, fishing effort in the lobster fishery (Panulirus argus), has gradually declined in subsequent years, with nearly a halving of the effort between 2015 and 2020. The resulting landings of lobster have shown a similar pattern with an increase up to 2015 when they amounted to 78t, and, after a period of relative stability in 2016-2017, showed a marked decline to 27t in 2018, before partial recovery in 2019 and 2020. Increasing landings per unit effort (number per trip) indicate that the formerly reduced lobster abundance, which had been declining since 2000 and which reached its lowest level in 2011, has subsequently increased relatively steadily all through 2020, back to levels close to those of 2007. Length based proxies for exploitation level with respect to MSY suggest that there has been overfishing of the stock (F/FMSY >1) for all the period covered by the data, and the mean size of the lobsters landed has been decreasing over the last 5 years.

Lobster fishery fish bycatch

Mixed landings of reef fish in the lobster fishery have fluctuated between 7 and 15t annually. The biomass index derived from the LPUE of these bycatch species also shows a decrease of about 35% from high levels in 2000 and 2007 to lowest levels in 2011. After a partial recovery from 2011 to 2013, the biomass declined slowly until 2018, and then rose sharply in 2019. Among the three main species landed, two - the Queen triggerfish, Balistes vetula, and the white grunt, Haemulon album,- are being overfished according to length-based indicators while the Red hind, Epinephelus guttatus, is being fully exploited (F/FMSY close to 1). Red fish trap fishery The figure below gives a summary of the trends in the red fish trap fishery, which principally targets a mix of deep water snappers such as the Silk snapper, Lutjanus vivanus, the Vermillion snapper, Rhomboplites aurorubens, the Blackfin snapper, Lutjanus buccanella and the Lane snapper, Lutjanus synagris. In the redfish trap fishery (Lutjanidae), the number of trips has grown from 335 to 566 (corresponding to 10 000 and 13 400 traps set respectively) during the period 2012 to 2016 but dropped considerably to 271 trips in 2017 (5 600 traps). In the last three years, the effort increased again to reach nearly 600 trips in 2020 (16 000 traps), the highest effort for the whole period considered. The landings of redfish (mainly silk snapper and in smaller proportions blackfin and vermillion snapper) broadly followed the variation of the effort, with the highest estimates (>50t) for the last two years, recovering from a low value in 2017 (25t). This drop in snapper landings and effort in 2017 is the consequence of a 6- month closed season voluntarily implemented by the fishermen that year (Graaf et al. 2017).

The biomass index derived from the LPUEs shows a decrease of 50% between 2007 and 2011, followed by a steady increase until 2019 and a sharp decrease in 2020. Length-based indicators for fishing mortality indicate that silk snapper and vermillion snapper have been heavily overfished, with a ratio F/FMSY higher than 1.3. For the other two snapper species (but also for the vermilion snapper in the most recent years), the length composition data is scarce which results in a large uncertainty. Nevertheless, the F/FMSY proxy also suggests that these two stocks are subject to overfishing although this is less pronounced than for the two principal species.

Other fishing métiers

Bottom drop longline, pelagic and bycatch landings have remained much less important and have shown no significant new developments

Overall conclusion

For both the targeted lobster and “redfish” stocks, the LPUE based indices indicate that stock size overall increased since the beginning of the current port sampling program (2011), when they were at a lower level. In this report, length-based indicators of fishing mortality levels are presented for the first time. This provides new insights on the exploitation status of the stocks. These indicators suggest that, despite the overall increase in stock size, the stocks are subject to overfishing, slightly for the lobsters, but more severely for the redfish. With the current declining trend in effort for the lobster fishery, it can be expected that the fishing mortality is declining. It is important to continue monitoring the fishery (and particularly length measurements of the landings) to see if the length-based indicator will reflect such a decline in fishing mortality in coming years. The situation is more worrying for the redfish fishery for which the recent trend is an increase in the fishing effort. This, combined with the indication that the fishing mortality of these stocks has been well above FMSY, suggest that management action is needed to bring the fishing mortality to lower levels. Again, continued monitoring of the fishery is essential, as well as improved biological sampling and reporting of the catches. The current ability to accurately estimate the status of individual redfish species is limited by the fact that the fisheries data is not reported by species. Being able to split the landings per species, either by encouraging the fishers to report landings per species, or by increasing the intensity of biological sampling, would, on the long term, provide a better basis to manage the “redfish” snapper stocks. The present study further suggests that three key finfish species, which are mainly landed as bycatch from the lobster fishery, are either being overfished (Queen triggerfish and White grunt) or are at the verge of being overfished (Red hind). The Queen triggerfish and Red hind formerly were common in the landings in the Dutch Caribbean but now still only have significant populations on the Saba Bank. Therefore, both of these species require a cautionary management approach as well.