Assessment of the Commercial Fishery of Saba Bank
The commercial fishery of Saba Bank, Netherlands Antilles, was assessed for six months from June 1 through November 30, 2007, by conducting port sampling interviews with Saban commercial fishermen to obtain information on fishing effort, gear usage, landings and species composition of catches. Results from our survey are compared to previous studies to provide an updated assessment of the Saba Bank commercial fishery.
The fishery can be summarized as follows. A small fishing fleet of approximately ten vessels operates from Fort Bay, Saba Island, and conducts small-scale commercial fishing on Saba Bank. Saban commercial fishermen may participate in either or both of two distinct types of fisheries: a lobster trap fishery and a “redfish” trap fishery. The two trap fisheries account for almost all commercial landings while other fishing methods (e.g. hook & line) make only a minor contribution to total landings from Saba Bank. Specific patterns of effort, landings and catch composition are identified within each trap fishery.
Lobster trap fishing is the more prevalent and economically significant Saba Bank fishery. Lobster catch rate is 0.84 lobster per trap-haul and 184 pounds per trip. Catch rates vary significantly with season. Projected annual lobster landings are 184,000 lbs (83.6 mt) with an exvessel value of US $1.3 million per year. The lobster trap fishery also harvests a diversity of “mixed fish” (shallow water reef fishes). Average catch rate of mixed fish is 0.5 pounds per traphaul and 37.8 pounds per trip, with projected annual mixed fish landings of 37,700 pounds (17.1 mt) at an ex-vessel value of US $68,700 per year.
The fish trap fishery targets “redfish” - an assortment of deepwater snapper species that is dominated by silk snapper, blackfin snapper, and vermilion snapper. These three lutjanid species comprise > 91 % of fish trap catch. Average catch rate of redfish in fish traps is 10 pounds per trap-haul, and 291 pounds per trip. Projected annual fish trap landings of redfish are 90,800 pounds (41.3 mt) with an ex-vessel value of US $289,000 per year. Fish trap landings also include a small quantity of mixed fish (< 9 % by weight of finfish in fish trap landings) comprised of a diversity of species but dominated by red hind and lane snapper. Catch rate of mixed fish in fish traps is 1 pound per trap haul and 27 pounds per trip.
Viewed as a whole, 2007 landings from Saba Bank by Saban commercial fishermen are projected to exceed 145 metric tons in 2007 with an ex-vessel value greater than US $1.6 million. Comparison to previous fisheries studies indicates that the Saba Bank commercial fishery is relatively stable in terms of total fishing effort, total landings, economic value, and fishing methods. The following trends were identified. Compared to 1999-2000, lobster catch rate in 2007 was approximately 33 % lower in terms of weight per trap-day, but there was only a small (6.3 %) reduction in total landings of lobster. A shift to smaller lobster size was not indicated by length frequencies: average carapace length was larger in 2007 (11.2 cm) than in 1999-2000 (10.7 cm). However, lobster fishing effort as measured by trap haul rate was 31 % greater in 2007 (80.9 trap-hauls per trip) than in 1999-2000 (62.0 trap-hauls per trip). We estimate that the total number of lobster traps in use on Saba Bank increased from 1,426 traps in 1999-2000 to 1,862 traps in 2007. Collectively, these findings indicate that Saba Bank fishermen of 2007 exert a greater fishing effort in order to maintain lobster landings at year 2000 levels. An increase in fishing effort coupled with a decrease in observed catch rate could suggest that lobster harvests are now at or exceed the maximum sustainable yield for Saba Bank stocks. However, more definitive conclusions about trends in lobster stock abundance are not possible owing to the limited time frame of available fisheries data sets.
The importance of redfish, as a percentage of total annual landings, has increased by three-fold since 2000. Yet, the Saba Bank redfish fishery is characterized by a lack of information. Stock densities are either unknown, or may be based on very optimistic calculations. The commercial fishery now harvests redfish primarily with fish traps, in contrast to hook & line fishing methods that predominated in 2000. Given that stock size remains poorly known, the current practice of harvesting almost exclusively juvenile fishes is a risky fisheries strategy. If reproductive output by silk snapper stocks is sufficiently reduced by harvesting it may lead to abrupt population declines or even a stock crash.
We recommend that the following actions should be priorities for management of Saba Bank fisheries resources: establishment of a program for long-term commercial fisheries monitoring, elimination of anchoring by large vessels on Saba Bank, development of a framework for monitoring and regulating the harvest of deepwater snappers, implementation of conservation measures to protect a red hind spawning aggregation, and initiation of a study to evaluate ghost fishing by lost traps.