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 |
---|---|---|
WSH | GREAT WHITE SHARK | Carcharodon carcharias |
TSK | FLAPNOSE HOUNDSHARK | Scylliogaleus quecketti |
TRB | WHITETIP REEF SHARK | Triaenodon obesus |
TIG | TIGER SHARK | Galeocerdo cuvier |
THR | THRESHER SHARKS NEI | Alopias spp. |
SUN | OCELLATED ANGELSHARK | Squatina tergocellatoides |
SSQ | VELVET DOGFISH | Scymnodon squamulosus |
SPZ | SMOOTH HAMMERHEAD | Sphyrna zygaena |
SPQ | SMALLEYE HAMMERHEAD | Sphyrna tudes |
SPN | HAMMERHEAD SHARKS NEI | Sphyrna spp. |
SPL | SCALLOPED HAMMERHEAD | Sphyrna lewini |
SPK | GREAT HAMMERHEAD | Sphyrna mokarran |
SON | PACIFIC SLEEPER SHARK | Somniosus pacificus |
SMA | SHORTFIN MAKO | Isurus oxyrhinchus |
SKX | SHARKS, RAYS, SKATES, ETC. NEI | Elasmobranchii |
SKH | VARIOUS SHARKS NEI | Selachimorpha (Pleurotremata) |
SCK | KITEFIN SHARK | Dalatias licha |
SBL | BLUNTNOSE SIXGILL SHARK | Hexanchus griseus |
RUZ | GREENBACK STINGAREE | Urolophus viridis |
RUT | CROSSBACK STINGAREE | Urolophus cruciatus |
RSK | REQUIEM SHARKS NEI | Carcharhinidae |
RPZ | LONGCOMB SAWFISH | Pristis zijsron |
RPC | DWARF SAWFISH | Pristis clavata |
RHY | AUSTRALIAN SHARPNOSE SHARK | Rhizoprionodon taylori |
RHN | WHALE SHARK | Rhincodon typus |
RHA | MILK SHARK | Rhizoprionodon acutus |
REO | SHARK SUCKER | Remora remora |
PTH | PELAGIC THRESHER SHARK | Alopias pelagicus |
PSK | CROCODILE SHARK | Pseudocarcharias kamoharai |
PPC | LONGNOSE SAWSHARK | Pristiophorus cirratus |
POR | PORBEAGLE SHARK | Lamna nasus |
OSF | ZEBRA SHARK | Stegostoma fasciatum |
ORZ | TAWNY NURSE SHARK | Nebrius ferrugineus |
ODH | BIGEYE SAND TIGER SHARK | Odontaspis noronhai |
OCS | OCEANIC WHITETIP SHARK | Carcharhinus longimanus |
NTC | BROADNOSE SEVENGILL SHARK | Notorynchus cepedianus |
NGA | SICKLEFIN LEMON SHARK | Negaprion acutidens |
MTL | SPOTTED ESTUARY SMOOTH-HOUND | Mustelus lenticulatus |
MSK | MACKEREL SHARKS, PORBEAGLES NEI | Lamnidae |
MAK | MAKO SHARKS | Isurus spp. |
LMP | MEGAMOUTH SHARK | Megachasma pelagios |
LMD | SALMON SHARK | Lamna ditropis |
LMA | LONGFIN MAKO | Isurus paucus |
LES | LEOPARD SHARK | Triakis semifasciata |
ISB | COOKIE CUTTER SHARK | Isistius brasiliensis |
HXT | SHARPNOSE SEVENGILL SHARK | Heptranchias perlo |
HEG | CRESTED BULLHEAD SHARK | Heterodontus galeatus |
HEE | SNAGGLETOOTH SHARK | Hemipristis elongatus |
HDQ | BULLHEAD SHARKS | Heterodontiformes |
HAH | BRISTLY CATSHARK | Halaelurus hispidus |
GAG | SCHOOL SHARK | Galeorhinus galeus |
FAL | SILKY SHARK | Carcharhinus falciformis |
EUB | WINGHEAD SHARK | Eusphyra blochii |
ETF | BLACKBELLY LANTERNSHARK | Etmopterus lucifer |
DWS | DEEP-WATER SHARKS (NEI) | Elasmobranchii |
DUS | DUSKY SHARK | Carcharhinus obscurus |
DOP | SHORTNOSE SPURDOG | Squalus megalops |
DGZ | DOGFISHES NEI | Squalus spp |
DGX | DOGFISH SHARKS NEI | Squalidae |
DGS | PICKED DOGFISH | Squalus acanthias |
DCA | BIRDBEAK DOGFISH | Deania calcea |
CYU | PLUNKET SHARK | Scymnodon plunketi |
CVX | GROUND SHARKS | Carcharhiniformes |
CTU | GUMMY SHARK | Mustelus antarcticus |
CPU | LITTLE GULPER SHARK | Centrophorus uyato |
CPS | DRAUGHTSBOARD SHARK | Cephaloscyllium isabellum |
CNX | WHITENOSE SHARK | Nasolamia velox |
CHB | GHOST SHARK | Callorhinchus milii |
CEU | DUMB GULPER SHARK | Centrophorus harrissoni |
CEM | SMALLFIN GULPER SHARK | Centrophorus moluccensis |
CCZ | CREEK WHALER | Carcharhinus fitzroyensis |
CCY | GRACEFUL SHARK | Carcharhinus amblyrhynchoides |
CCU | AUSTRALIAN BLACKTIP SHARK | Carcharhinus tilstoni |
CCT | GREY NURSE/ SAND TIGER SHARK | Carcharius taurus |
CCQ | SPOTTAIL SHARK | Carcharhinus sorrah |
CCP | SANDBAR SHARK | Carcharhinus plumbeus |
CCM | HARDNOSE SHARK | Carcharhinus macloti |
CCL | BLACKTIP SHARK | Carcharhinus limbatus |
CCG | GALAPAGOS SHARK | Carcharhinus galapagensis |
CCF | PIGEYE SHARK | Carcharhinus amboinensis |
CCE | BULL SHARK | Carcharhinus leucas |
CCD | WHITECHEEK SHARK | Carcharhinus dussumieri |
CCB | SPINNER SHARK | Carcharhinus brevipinna |
CCA | BIGNOSE SHARK | Carcharhinus altimus |
BTH | BIGEYE THRESHER SHARK | Alopias superciliosus |
BSK | BASKING SHARK | Cetorhinus maximus |
BSH | BLUE SHARK | Prionace glauca |
BRO | BRONZE WHALER SHARK | Carcharhinus brachyurus |
BLR | BLACKTIP REEF SHARK | Carcharhinus melanopterus |
ASK | ANGELSHARKS, SAND DEVILS NEI | Squatinidae |
AML | GREY REEF SHARK | Carcharhinus amblyrhynchos |
ALV | COMMON THRESHER SHARK | Alopias vulpinus |
ALS | SILVERTIP SHARK | Carcharhinus albimarginatus |