Incidental shark and ray capture occurs in longline, purse seine and gillnet tuna fisheries. The most effective mitigation measures for longline fisheries include deep-setting, reduced soak time, avoiding wire leaders and hook and bait changes [2], though in applying these, cross-taxa effects need careful consideration. Silky and oceanic whitetip sharks are the most common shark bycatch species in purse seine fisheries, captured mostly when vessels fish on FADs but also through entanglement in FAD netting. Limiting FAD use and modifying FAD designs and practices are the most promising mitigation methods [2]. As with cetaceans, entanglement is a significant problem in medium-scale, semi-industrial and artisanal tuna drift gillnet fisheries. There has been some success with sub-surface gillnets [3] but further validation of this technique is required. For all gear types, safe handling and release procedures have been developed which significantly reduce post-release mortality of sharks, e.g., try to avoid landing sharks onboard; instead bring them close to the vessel and cut line as close to the hook as possible to reduce the length of trailing line [1].
Recent studies have looked at physiological factors affecting post-release mortality of sharks, e.g., stationary-respiring shark species have been shown to experience lower post-release mortality rates than obligate ram-ventilators on longlines [2]. Such information helps to understand the vulnerability of different shark species and thus feeds into improved management strategies for shark bycatch.
For detailed biological and distributional data about shark species, refer to FishBase, Sharkipedia (includes abundance time-series) or Shark-References. FAO has published a series of regional catalogues describing shark/ batoid/chimeras, such as this one for the North Atlantic. Look for others in the series here. NOAA's 'Find a Species - Highly Migratory Species' has information on protection status, biology and population status, distribution, threats, conservation measures and research. See also FAO's database of management measures. Handy species ID guides can be found here.
STAGIS, a database of shark tagging FIELD STUDIES conducted in the Pacific Ocean, can be accessed here.
References
- Francis MP, Lyon WS, Clarke SC, et al (2023) Post-release survival of shortfin mako (Isurus oxyrinchus) and silky (Carcharhinus falciformis) sharks released from pelagic tuna longlines in the Pacific Ocean. Aquatic Conservation: Marine and Freshwater Ecosystems 33:366–378. https://doi.org/10.1002/aqc.3920
- Dapp DR, Huveneers C, Walker TI, et al (2016) Moving from Measuring to Predicting Bycatch Mortality: Predicting the Capture Condition of a Longline-Caught Pelagic Shark. Front Mar Sci 2:126. https://doi.org/10.3389/fmars.2015.00126
- Swimmer Y, Zollett E, Gutierrez A (2020) Bycatch mitigation of protected and threatened species in tuna purse seine and longline fisheries. Endang Species Res 43:517–542. https://doi.org/10.3354/esr01069
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Moazzam M (2019) Species composition of elasmobranchs in the surface and subsurface gillnet operation in the Northern Arabian Sea. In: IOTC - 15th Working Party on Ecosystems and Bycatch. IOTC-2019-WPEB15-13, La Saline Les Bains, Reunion Island
Sharks
3-Alpha Code | Name | Scientific Name |
---|---|---|
ASK | ANGELSHARKS, SAND DEVILS NEI | Squatinidae |
CCU | AUSTRALIAN BLACKTIP SHARK | Carcharhinus tilstoni |
RHY | AUSTRALIAN SHARPNOSE SHARK | Rhizoprionodon taylori |
BSK | BASKING SHARK | Cetorhinus maximus |
ODH | BIGEYE SAND TIGER SHARK | Odontaspis noronhai |
BTH | BIGEYE THRESHER SHARK | Alopias superciliosus |
CCA | BIGNOSE SHARK | Carcharhinus altimus |
DCA | BIRDBEAK DOGFISH | Deania calcea |
ETF | BLACKBELLY LANTERNSHARK | Etmopterus lucifer |
BLR | BLACKTIP REEF SHARK | Carcharhinus melanopterus |
CCL | BLACKTIP SHARK | Carcharhinus limbatus |
BSH | BLUE SHARK | Prionace glauca |
SBL | BLUNTNOSE SIXGILL SHARK | Hexanchus griseus |
HAH | BRISTLY CATSHARK | Halaelurus hispidus |
NTC | BROADNOSE SEVENGILL SHARK | Notorynchus cepedianus |
BRO | BRONZE WHALER SHARK | Carcharhinus brachyurus |
CCE | BULL SHARK | Carcharhinus leucas |
HDQ | BULLHEAD SHARKS | Heterodontiformes |
ALV | COMMON THRESHER SHARK | Alopias vulpinus |
ISB | COOKIE CUTTER SHARK | Isistius brasiliensis |
CCZ | CREEK WHALER | Carcharhinus fitzroyensis |
HEG | CRESTED BULLHEAD SHARK | Heterodontus galeatus |
PSK | CROCODILE SHARK | Pseudocarcharias kamoharai |
RUT | CROSSBACK STINGAREE | Urolophus cruciatus |
DWS | DEEP-WATER SHARKS (NEI) | Elasmobranchii |
DGX | DOGFISH SHARKS NEI | Squalidae |
DGZ | DOGFISHES NEI | Squalus spp |
CPS | DRAUGHTSBOARD SHARK | Cephaloscyllium isabellum |
CEU | DUMB GULPER SHARK | Centrophorus harrissoni |
DUS | DUSKY SHARK | Carcharhinus obscurus |
RPC | DWARF SAWFISH | Pristis clavata |
TSK | FLAPNOSE HOUNDSHARK | Scylliogaleus quecketti |
CCG | GALAPAGOS SHARK | Carcharhinus galapagensis |
CHB | GHOST SHARK | Callorhinchus milii |
CCY | GRACEFUL SHARK | Carcharhinus amblyrhynchoides |
SPK | GREAT HAMMERHEAD | Sphyrna mokarran |
WSH | GREAT WHITE SHARK | Carcharodon carcharias |
RUZ | GREENBACK STINGAREE | Urolophus viridis |
CCT | GREY NURSE/ SAND TIGER SHARK | Carcharius taurus |
AML | GREY REEF SHARK | Carcharhinus amblyrhynchos |
CVX | GROUND SHARKS | Carcharhiniformes |
CTU | GUMMY SHARK | Mustelus antarcticus |
SPN | HAMMERHEAD SHARKS NEI | Sphyrna spp. |
CCM | HARDNOSE SHARK | Carcharhinus macloti |
SCK | KITEFIN SHARK | Dalatias licha |
LES | LEOPARD SHARK | Triakis semifasciata |
CPU | LITTLE GULPER SHARK | Centrophorus uyato |
RPZ | LONGCOMB SAWFISH | Pristis zijsron |
LMA | LONGFIN MAKO | Isurus paucus |
PPC | LONGNOSE SAWSHARK | Pristiophorus cirratus |
MSK | MACKEREL SHARKS, PORBEAGLES NEI | Lamnidae |
MAK | MAKO SHARKS | Isurus spp. |
LMP | MEGAMOUTH SHARK | Megachasma pelagios |
RHA | MILK SHARK | Rhizoprionodon acutus |
OCS | OCEANIC WHITETIP SHARK | Carcharhinus longimanus |
SUN | OCELLATED ANGELSHARK | Squatina tergocellatoides |
SON | PACIFIC SLEEPER SHARK | Somniosus pacificus |
PTH | PELAGIC THRESHER SHARK | Alopias pelagicus |
DGS | PICKED DOGFISH | Squalus acanthias |
CCF | PIGEYE SHARK | Carcharhinus amboinensis |
CYU | PLUNKET SHARK | Scymnodon plunketi |
POR | PORBEAGLE SHARK | Lamna nasus |
RSK | REQUIEM SHARKS NEI | Carcharhinidae |
LMD | SALMON SHARK | Lamna ditropis |
CCP | SANDBAR SHARK | Carcharhinus plumbeus |
SPL | SCALLOPED HAMMERHEAD | Sphyrna lewini |
GAG | SCHOOL SHARK | Galeorhinus galeus |
REO | SHARK SUCKER | Remora remora |
SKX | SHARKS, RAYS, SKATES, ETC. NEI | Elasmobranchii |
HXT | SHARPNOSE SEVENGILL SHARK | Heptranchias perlo |
SMA | SHORTFIN MAKO | Isurus oxyrhinchus |
DOP | SHORTNOSE SPURDOG | Squalus megalops |
NGA | SICKLEFIN LEMON SHARK | Negaprion acutidens |
FAL | SILKY SHARK | Carcharhinus falciformis |
ALS | SILVERTIP SHARK | Carcharhinus albimarginatus |
SPQ | SMALLEYE HAMMERHEAD | Sphyrna tudes |
CEM | SMALLFIN GULPER SHARK | Centrophorus moluccensis |
SPZ | SMOOTH HAMMERHEAD | Sphyrna zygaena |
HEE | SNAGGLETOOTH SHARK | Hemipristis elongatus |
CCB | SPINNER SHARK | Carcharhinus brevipinna |
CCQ | SPOTTAIL SHARK | Carcharhinus sorrah |
MTL | SPOTTED ESTUARY SMOOTH-HOUND | Mustelus lenticulatus |
ORZ | TAWNY NURSE SHARK | Nebrius ferrugineus |
THR | THRESHER SHARKS NEI | Alopias spp. |
TIG | TIGER SHARK | Galeocerdo cuvier |
SKH | VARIOUS SHARKS NEI | Selachimorpha (Pleurotremata) |
SSQ | VELVET DOGFISH | Scymnodon squamulosus |
RHN | WHALE SHARK | Rhincodon typus |
CCD | WHITECHEEK SHARK | Carcharhinus dussumieri |
CNX | WHITENOSE SHARK | Nasolamia velox |
TRB | WHITETIP REEF SHARK | Triaenodon obesus |
EUB | WINGHEAD SHARK | Eusphyra blochii |
OSF | ZEBRA SHARK | Stegostoma fasciatum |