Haan, D. de

Humpback and minke whale acoustic presence with reference to fish sounds and ambient noise levels at Saba Bank, Caribbean Windward Dutch Islands

The Antillean Island chain is a known breeding and calving ground for North Atlantic humpback whales (Megaptera novaeangliae). However, while most research efforts for this species have focused on the largest aggregation of whales, located on Silver Bank, off the northern coast of the Dominican Republic, there are still significant knowledge gaps with respect to humpback whale movements along the Antillean Island chain. Even less is known about the spatio-temporal distribution of other marine mammal and fish species in the region. This report summarizes analysis results of acoustic data (10-8000 Hz effective analysis bandwidth recorded at a 25% duty cycle), recorded on the north east of Saba Bank from October 2011 to April 2012. The results show the consistent presence of humpback whales in the vicinity of Saba Bank during their winter breeding season, occasional presence of minke whales and the presence of sound producing fish assemblages. Humpback whale song occurred from the end of December to the end of the recording period in April. From February to April humpback whale song was recorded on more than 89 % of all recording days, though it occurred most frequently in March. All recording days in March showed song presence, with an average of 8.5 ± 2.8 (mean ± SE) hours of recorded song per day. In contrast, for minke whale (Balaenoptera acutorostrata) 48 pulse trains (n = 32) were detected less frequently between February to April 2012. A variety of unidentified fish sounds were present throughout the recordings. Although the occurrence of these sounds was not quantified, notable fish choruses (e.g. grouper spp. Epinephelinae) consisting of one to two distinct pulsed calls in the frequency range of 100 - 600 Hz were documented from October to December 2011 in particular. The results of this pilot project highlight the feasibility of using passive acoustic monitoring (PAM) to explore year-round marine mammal and fish presence and distribution in otherwise understudied and remote field sites.

Date
2020
Data type
Research report
Theme
Research and monitoring
Report number
C067/16
Geographic location
Saba bank

Priorities in management implementation for marine mammal conservation in the Saba sector of the Yarari sanctuary

The Yarari Marine Mammal Sanctuary (hereafter simply referred to as the Yarari Sanctuary, or Yarari) was formally established on September 2, 2015. It is currently composed of two sectors: one surrounding Saba and the Saba Bank and one covering the EEZ waters of Bonaire. In order to help establish an effective cetacean conservation management plan for the Saba and Saba Bank sector of the sanctuary we here review the main marine mammal threats, help identify main management goals and make both governance and management recommendations based both on stakeholder interviews and a management review of functioning marine mammal sanctuaries in the Western Atlantic.

There are 8 species of marine mammals known to occur in the windward Dutch Caribbean Yarari Sanctuary. The sanctuary has relatively low levels of human activity. Based on our review, cumulative contaminant impacts – such as oil contamination originating from St. Eustatius – are potentially highest, followed by collision impacts due to the relatively high level of shipping traffic. Other factors such as, fishery entanglement, bycatch-impacts and marine debris impacts are likely low compared to many areas directly outside the sanctuary. While whale & dolphin watching impacts are still probably negligible, the impacts of anthropogenic noise, climate-change impacts and cumulative impacts still remain unknown but are potentially high.

Five main clusters of interrelated goals and objectives were identified based on expert and management stakeholder interviews. The most essential proximate goal for management should be to establish a minimum structural level of institutional capacity. Under the reigning conditions of resource limitation, the next key goal should be to establish effective collaboration towards jointly achieving the higher management goals and objectives.

Based on our review of species, threats, operations of other sanctuaries and expert and stakeholder input we list 23 priority recommendations and action points towards implementation of cetacean conservation for the Saba and Saba Bank Yarari sector. 

           Governance

  • Use the Saba Bank Management Unit (SMBU) governance model for Yarari management

    implementation.

  • Consider merging Yarari tasks into the SMBU to effectuate resource pooling and prevent

    management fragmentation.

  • Legal resources
  • Design and implement a simple legal mandate for Yarari management.
  • Copy and implement international legal guidelines for whale watching.
  • Revise the Fishery Framework Act BES (Vissery Visserijwet besluit BES) or draft a Decree

    (Regeling) under the Nature Conservation Framework Act BES (Wet Grondslagen Natuurbeheer en-bescherming, WGN) to forbid all forms of pelagic (not benthic) longline and purse seine fishing in Yarari waters.

  • Devise and implement legal measures and guidelines to safeguard Yarari from anthropogenic noise pollution.
  • Finances
  • Based on the review of functioning sanctuaries, and current stressor levels, a basic annual budget of US$ 150 K will be sufficient to implement satisfactory marine mammal conservation.
  • Focus expenditures on management development, outreach and international cooperation.
  • Limit expenditures on costly enforcement and research. Participation in these activities should principally be limited to essential monitoring and practical support of collaborating parties. 

           Personnel and logistics

  • Based on the review of functioning sanctuaries, two (additional) personnel members are

    sufficient to effectuate adequate Yarari cetacean conservation.

  • The combined personnel should include both technical and boat handling skills as well as

    management development skills for effective local and international policy development

    support and cooperation.

  • Saba island is the logical choice for basing Yarari headquarters.
  • A larger vessel (than the current Queen Beatrix) is needed for safer and more effective

    operation in Yarari waters.

    Management priorities

  • Aim for sanctuary expansion to include St. Maarten and St. Eustatius marine waters (and

    ultimately also Curaçao and Aruba EEZ waters).

  • Establish and expand cooperation with local enforcement and research partners.
  • Develop close ties with local stakeholders and encourage their active involvement.
  • Actively represent Yarari interests in regional marine mammal policy development and

    research initiatives.

    Research priorities

  • Use remote methods (AIS) and current port fishery sampling to monitor fishery activity, and

    ship traffic inside Yarari.

  • Use passive acoustic monitoring and sighting records to monitor cetacean distribution and

    abundance.

  • Use passive acoustic monitoring to measure and follow background noise levels.
  • Record and collect data on and specimens from stranding incidents using published guidelines

    and protocols.

  • Subsample stranding fatalities to determine contaminant loads of the cetaceans inside Yarari

    and their prey species.

  • Document the abundance and source of marine debris found in the sanctuary. 
Date
2017
Data type
Research report
Theme
Governance
Report number
C097/17
Geographic location
Bonaire
Saba
Saba bank

Humpback and minke whale acoustic presence with reference to fish sounds and ambient noise levels at Saba Bank, Caribbean Windward Dutch Islands

The Antillean Island chain is a known breeding and calving ground for North Atlantic humpback whales (Megaptera novaeangliae). However, while most research efforts for this species have focused on the largest aggregation of whales, located on Silver Bank, off the northern coast of the Dominican Republic, there are still significant knowledge gaps with respect to humpback whale movements along the Antillean Island chain. Even less is known about the spatio-temporal distribution of other marine mammal and fish species in the region. This report summarizes analysis results of acoustic data (10- 8000 Hz effective analysis bandwidth recorded at a 25% duty cycle), recorded on the north east of Saba Bank from October 2011 to April 2012. The results show the consistent presence of humpback whales in the vicinity of Saba Bank during their winter breeding season, occasional presence of minke whales and the presence of sound producing fish assemblages. Humpback whale song occurred from the end of December to the end of the recording period in April. From February to April humpback whale song was recorded on more than 89 % of all recording days, though it occurred most frequently in March. All recording days in March showed song presence, with an average of 8.5 ± 2.8 (mean ± SE) hours of recorded song per day. In contrast, for minke whale (Balaenoptera acutorostrata) 48 pulse trains (n = 32) were detected less frequently between February to April 2012. A variety of unidentified fish sounds were present throughout the recordings. Although the occurrence of these sounds was not quantified, notable fish choruses (e.g. grouper spp. Epinephelinae) consisting of one to two distinct pulsed calls in the frequency range of 100 - 600 Hz were documented from October to December 2011 in particular. The results of this pilot project highlight the feasibility of using passive acoustic monitoring (PAM) to explore year-round marine mammal and fish presence and distribution in otherwise understudied and remote field sites. 

Date
2016
Data type
Research report
Theme
Research and monitoring
Report number
C067/16
Geographic location
Saba bank