Marine Mammals

Cetaceans are the principal marine mammals affected by tuna fisheries. They may be incidentally captured in purse seines and 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 fishermen 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]. Progress in the development of dynamic spatial fishery management strategies will 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]. Fishing area closures are utilised in the interim. 'Weak' circle hooks and strong branchlines are required in the Hawaii-based deep-set and shallow-set longline fisheries (see NOAA's Whale link below). They can reduce bycatch (but not depredation), though post-interaction mortality is unknown.

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

 

Dolphins

Species

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