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Dolphin Landings in the Western Central Atlantic Ocean

Ongoing research by the Beyond Our Shores Foundation (BOSF) shows U.S. recreational landings from the Gulf of Mexico, South Atlantic Bight, Mid-Atlantic Bight, and New England constitute the largest component of recorded landings when compared to countries that submit dolphinfish commercial landings to the Food and Agriculture Organization (FAO) for the Western Central Atlantic (WCA) Ocean.  Not included in this graph, however, are 16 nations within the WCA that do not submit dolphinfish commercial landings to the FAO as well as recreational landings for jurisdictions throughout the Caribbean Sea and Tropical Atlantic; this data is needed in order to gather a more complete view of annual landings that can be used to better assess seasonal and interannual population trends.  In addition, there are several unknowns related to the level of misreporting for nations that do submit

Fig. 1 - U.S. recreational dolphinfish landings as well as the top 8 nations that have submitted dolphinfish commercial landings to the FAO since 1956. The "Other Countries" category represents 11 nations that began submitting commercial landings data in the mid '90s.

landings data as well as the level of dolphin bycatch among international longline vessels in the WCA (Fig. 4 below).  Over the past month, BOSF has given two webinars to the South Atlantic Fishery Management Council (SAFMC) to update the Council on research conducted to date for the Dolphinfish Research Program (DRP) which included a detailed look at data collected throughout the tagging program as well as ongoing research in order to better document regional dolphinfish landings and fishing effort.  These seminars were conducted upon request from SAFMC as the Council continues to gather information relative to Amendment 10 to the Dolphin Wahoo Fishery Management Plan.  To review the slides we submitted to the SAFMC prior to the webinar please click here.  The slides provide a fairly comprehensive review of research associated with the tagging program as well as additional slides on landings and effort data collected over the past several months.  Here, we provide a brief overview of our research strategy on the latter. 

In 1999, Dr. Robin Mahon published a paper entitled “Dolphinfish fisheries in the Caribbean Region” in Scientia Marina, a marine and fisheries science journal based in Barcelona, Spain, that provided the first thorough categorization of dolphinfish landings and fleet dynamics throughout the Caribbean Sea.  Dr. Mahon used data up to 1995.  Using Dr. Mahon’s work as a model, we have started to append 23 years of data to specific themes in his paper including trends in fishing effort for large pelagics, artisanal and small-scale fleets, large-scale commercial fleets; recreational fleets; fish aggregating devices (FADs), and trends in landings.   


Figure 2 Extending out Dr. Mahon’s time-series shows the expansion and contraction of eight nations that have been reporting dolphinfish commercial landings since the 50s and 60s. In the mid-90s, 11 nations began to report dolphinfish commercial landings showing an increase in overall landings over the 67-year period. Note that Figure 1 above contains the commercial landings data from 1995 onward.

We have initiated conversations with many scientists around the region to gather information on those themes in effort to better categorize dolphinfish landings and effort throughout the Western Central Atlantic Ocean.  Why do this?  There are several reasons.  First, at the highest level and as stated in Mahon’s paper, a modern stock assessment for dolphinfish has not been conducted in the Western Central Atlantic Ocean largely because attention is directed toward other large pelagic fishes, mainly tunas and billfishes, in ICCAT or at NOAA’s Southeast Fisheries Science Division.  Secondly, there are several anecdotal reports from taggers and observations from our tagging program listed below by region that suggest changes to population dynamics:

Table 1 Anecdotal reports from taggers and observations from the DRP listed below by region that suggest changes to population dyanmics.
Region or Location and Observations
Mid-Atlantic Bight: Delayed start to season; Mostly small size fish (e.g., 15-25”) Dominican Republic: Increasing recoveries at FADs
South Atlantic Bight: Shortened Season Barbados: Sargassum leading to excellent catches year round
Florida Straits: Delayed start to the season; No large gaffer size fish (e.g., >36”) Cayman Islands: Shorter season and lack of defined season peak
U.S. Caribbean Sea: Out of season catches at FADs Cozumel: Size frequency changes - 20 lb fish to more 4 lb fish

Finally, there are several unknowns regarding misreported landings, lack of any landings data, lack of effort data, fleet size and fishing fleet characteristics, as well as the magnitude of unknowns regarding bycatch among large-scale commercial longline fishing operations and purse seine activity throughout the region.  An update to Mahon’s work will add to our understanding regarding dolphinfish fisheries throughout the WCA and serve as a similar undertaking that members states in the IATTC took to identify knowledge gaps and areas to focus work before they conducted a stock assessment in the southern portion of the Eastern Pacific Ocean in 2018. 

Figure 3 A 62-year time-series of number of longline hooks set per year by seven main nations that have been reporting since the 50s and 60s and additional countries that started reporting in the 90s. (A) Effort in the Atlantic east of national EEZs and (B) effort within national EEZs.
Figure 4 A 62 year time-series of ICCAT Task II longline effort data (5 deg x 5 deg) for the WECAFC region (bounding box). The red ovals represent effort from 2016 to 2018. The partition in the bounding box represents Mahon’s division of the effort into two separate regions: Effort in the Atlantic east of national EEZs and effort within national EEZs. See Figure 3 for more.
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