Marine Mammals

Cetaceans are the principal marine mammals affected by tuna fisheries. They may be incidentally captured in purse seines or become entangled or hooked on longlines (e.g., false killer whales in the Hawaii-based deep-set longline fishery). Entanglement is a significant problem in medium-scale, semi-industrial and artisanal tuna drift gillnet fisheries. In the tropical tuna purse-seine fishery, species such as baleen whales or dolphins (as well the whale shark Rhincodon typus), may serve as sighting cues by purse-seine fishers for the presence of tuna schools at the surface of the sea and/or may be caught accidentally when fishing for the targeted species [1].

Successful techniques to release cetaceans from purse seine nets have been employed for some time, e.g., the backdown procedure and Medina panel, and there have been advances in techniques for safe handling and release of megafauna from purse seines, longlines and gillnets [2,3,4]. Dynamic spatio-temporal fishery management strategies can help fishers to avoid interactions in the first place. For example, a recent study identified the principal environmental variables influencing the co-occurrence between baleen whales, whale sharks and tuna purse-seine fisheries [1].  'Weak' circle hooks can reduce bycatch (but not depredation), though post-interaction mortality is unknown. Sub-surface gillnets have been shown to reduce cetacean bycatch in Indian Ocean fisheries, though not for deep-diving cetaceans. Pingers (acoustic alarms) have been shown to mitigate bycatch of some cetacean species, predominantly in gillnet fisheries, albeit with strong caveats [5].

SeaLlifeBase is a source of biological and distribution data for marine mammal species. FAO's guide to the Marine Mammals of the World provides species identification and distribution information. Locate handy Species ID guides here. NOAA's 'Find a Species - Dolphins & Porpoises' and 'Whales' has information on protection status, biology and population status, distribution, threats, conservation measures and research. Cetacean mortality can be reduced by following techniques outlined in Guidelines for the safe and humane handling and release of bycaught small cetaceans from fishing gear.

References

  1. Escalle, L., Pennino, M.G., Gaertner, D., Chavance, P., Delgado de Molina, A., Demarcq, H., Romanov, E., and Merigot, B. 2016. Environmental factors and megafauna spatio-temporal co-occurrence with purse-seine fisheries. Fisheries Oceanography 25(4): 433–447. doi:10.1111/fog.12163.
  2. Escalle, L., Murua, H., Amande, J.M., Arregui, I., Chavance, P., Delgado de Molina, A., Gaertner, D., Fraile, I., Filmalter, J.D., Santiago, J., Forget, F., Arrizabalaga, H., Dagorn, L., and Merigot, B. 2016. Post-capture survival of whale sharks encircled in tuna purse-seine nets: tagging and safe release methods. Aquatic Conservation: Marine and Freshwater Ecosystems 26(4): 782–789. doi:10.1002/aqc.2662.
  3. Poisson, F., Vernet, A.L., Seret, B., and Dagorn, L. 2012. Good practices to reduce the mortality of sharks and rays caught incidentally by the tropical tuna purse seiners. EU FP7, EBFMtuna-2012 Montpellier, France.
  4. Hamer, D., Minton, G. 2020. Guidelines for the safe and humane handling and release of bycaught small cetaceans from fishing gear. CMS Technical Series No. 43. UNEP/CMS Secretariat, Bonn, Germany.
  5. FAO. 2021. Fishing operations. Guidelines to prevent and reduce bycatch of marine mammals in capture fisheries. FAO, Rome, Italy.

 

Dolphins

Marine Mammals

3-Alpha Code Name Scientific Name
SEA ANTARCTIC FUR SEAL Arctocephalus forsteri
SEK SOUTH AFRICAN FUR SEAL Arctocephalus pusillus
SGF GUADALUPE FUR SEAL Arctocephalus townsendi
SSF SUBANTARCTIC FUR SEAL Arctocephalus tropicalis
SPP SPECTACLED PORPOISE Australophocaena dioptrica
MIW MINKE WHALE Balaenoptera acutorostrata
SIW SEI WHALE Balaenoptera borealis
BRW BRYDE'S WHALE Balaenoptera edeni
BLW BLUE WHALE Balaenoptera musculus
FIW FIN WHALE Balaenoptera physalus
BEW BAIRD'S BEAKED WHALE Berardius bairdii
SEN NORTHERN FUR SEAL Callorhinus ursinus
WLE WHALE (UNIDENTIFIED) Cetacea
DLP DOLPHINS NEI Delphinidae
DCZ LONG-BEAKED COMMON DOLPHIN Delphinus capensis
DCO COMMON DOLPHIN Delphinus delphis
GRW GRAY WHALE Eschrichtius robustus
SSL STELLER SEA LION Eumetopias jubatus
KPW PYGMY KILLER WHALE Feresa attenuata
SHW SHORT-FINNED PILOT WHALE Globicephala macrorhynchus
PIW LONG-FINNED PILOT WHALE Globicephala melas
GLO PILOT WHALES NEI Globicephala spp
DRR RISSO'S DOLPHIN Grampus griseus
PYW PYGMY SPERM WHALE Kogia breviceps
DWW DWARF SPERM WHALE Kogia simus
FRD FRASER'S DOLPHIN Lagenodelphis hosei
DWP PACIFIC WHITE-SIDED DOLPHIN Lagenorhynchus obliquidens
DDU DUSKY DOLPHIN Lagenorhynchus obscurus
RNW NORTHERN RIGHT WHALE DOLPHIN Lissodelphis borealis
MAM AQUATIC MAMMALS NEI Mammalia
HUW HUMPBACK WHALE Megaptera novaeangliae
BBW BLAINVILLE'S BEAKED WHALE Mesoplodon densirostris
TGW GINKGO-TOOTHED BEAKED WHALE Mesoplodon ginkgodens
MEP BEAKED WHALES NEI Mesoplodon spp
SNP NORTHERN ELEPHANT SEAL Mirounga angustirostris
SMH HAWAIIAN MONK SEAL Monachus schauinslandi
MYS BALEEN WHALES NEI Mysticeti
ASL AUSTRALIAN SEA LION Neophoca cinerea
ODN TOOTHED WHALES NEI Odontoceti
KIW KILLER WHALE Orcinus orca
SXX SEALS NEI Otariidae, phocidae
MEW MELON-HEADED WHALE Peponocephala electra
SEC HARBOUR SEAL Phoca vitulina
PHR HARBOUR PORPOISE Phocoena phocoena
PDA DALL'S PORPOISE Phocoenoides dalli
SPW SPERM WHALE Physeter macrocephalus
FAW FALSE KILLER WHALE Pseudorca crassidens
DPN PANTROPICAL SPOTTED DOLPHIN Stenella attenuata
DST STRIPED DOLPHIN Stenella coeruleoalba
DSI SPINNER DOLPHIN Stenella longirostris
DSP SPOTTED DOLPHINS NEI Stenella spp.
RTD ROUGH-TOOTHED DOLPHIN Steno bredanensis
DBZ INDO-PACIFIC BOTTLENOSE DOLPHIN Tursiops aduncus
DBO BOTTLENOSE DOLPHIN Tursiops truncatus
CSL CALIFORNIA SEA LION Zalophus californianus
BCW CUVIER'S BEAKED WHALE Ziphius cavirostris