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