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Marine Mammal Assessments at the NEFSC
A major goal of the Marine Mammal Protection Act (MMPA) is to allow marine mammal populations to rebuild and remain at the population’s Optimum Sustainable Population level. To accomplish this goal the data collection and management scheme depicted below was developed. To go through this scheme, start with the programs that collect the basic data (human-induced mortalities, abundance, and stock structure). These data are then used to assess the status of each stock which is annually updated in the Stock Assessment Reports. A stock is considered “strategic” when the level of human-induced mortalities (such as by-catch in commercial fisheries and ship-strikes) is larger than the Potential Biological Removal (PBR) level. PBR is derived from abundance estimates and measures of uncertainty in the estimates of abundance and mortalities. According to the MMPA if a stock is considered strategic, then a Take Reduction Team (TRT) must be created to develop a Take Reduction Plan, which is a plan to reduce the mortalities to levels below PBR. The monitoring/data collection programs continue updating the mortality and abundance estimates. So, if updated estimates indicate that the level of human-induced mortality is above the PBR level then the Take Reduction Plan must be updated with the goal to reduce the levels of mortalities. The Scientific Review Group is an independent group of scientists that reviews the scientific issues involved in this scheme.
PSB and other parts of NMFS are involved in most of these steps within the data collection and management scheme.
In the Atlantic there are 5 TRTs to which PSB contributes information.
| TRT | SPECIES COMMON NAME | SPECIES SCIENTIFIC NAME | FISHERIES |
|---|---|---|---|
| Large whale TRT | North Atlantic right whale humpback whale fin whale minke whale |
Balaena mysticetus Megaptera novaeangliae Balaenoptera physalus Balaenoptera acutorostrata |
Northeast trap/pot Mid-Atlantic trap/pot Southeast trap/pot Northeast gillnet Mid-Atlantic gillnet Southeast gillnet |
| Atlantic trawl gear TRT | long-finned pilot whale short-finned pilot whale common dolphin white sided dolphin |
Globicephala melas Globicephala macrohynchus Delphinus delphis Lagenorhynchus acutus |
Mid-Atlantic mid-water trawl Mid-Atlantic bottom trawl Northeast mid-water trawl Northeast bottom trawl |
| Harbor porpoise TRT | Gulf of Maine/Bay of Fundy harbor porpoise |
Phocoena phocoena |
Northeast gillnet Mid-Atlantic gillnet |
| Coastal bottlenose dolphin TRT | coastal bottlenose dolphin |
Tursiops truncatus |
Mid-Atlantic gillnet Virginia pound net Mid-Atlantic haul/beach seine Atlantic blue crab trap/pot North Carolina inshore gillnet North Carolina roe mullet stop North Carolina long haul seine Southeastern US Atlantic shark gillnet Southeast Atlantic gillnet |
| Pelagic Longline TRT | long-finned pilot whale short-finned pilot whale |
Globicephala melas Globicephala macrohynchus |
Atlantic pelagic longline
|
Observer data needed to estimate by-catch rates in commercial fisheries is collected by the Northeast Fisheries Observer Program (NEFOP), also part of the NEFSC. PSB analyzes these observer data and uses additional databases to estimate bycatch that is attributed to commercial fisheries. PSB also uses the observer data to investigate what types of gear characteristics and environmental factors are associated with high bycatch. This type of information has been very helpful to the Take Reduction Teams in developing a plan to reduce bycatch.
PSB is also involved in collecting the needed data and analyzing those data to estimate abundance of cetaceans and seals.
