TY - JOUR
T1 - Results of a short study of interactions of cetaceans and longline fisheries in Atlantic waters
T2 - environmental correlates of catches and depredation events
AU - Hernandez-Milian, Gema
AU - Goetz, Sabine
AU - Varela-Dopico, Catuxa
AU - Rodriguez-Gutierrez, Jose
AU - Romon-Olea, Jorge
AU - Fuertes-Gamundi, Jose R.
AU - Ulloa-Alonso, Edelmiro
AU - Tregenza, Nick J. C.
AU - Smerdon, Andy
AU - Otero, Monserrat G.
AU - Tato, Vicente
AU - Wang, Jianjun
AU - Santos, M. Begona
AU - Lopez, Alfredo
AU - Lago, Rebeca
AU - Portela, Julio M.
AU - Pierce, Graham J.
PY - 2008/10
Y1 - 2008/10
N2 - In the Atlantic, economic losses have been reported from shark, swordfish and tuna longline fisheries due to depredation by cetaceans. We examined interactions of odontocete cetaceans with commercial longliners operating in waters off Brazil and the Azores archipelago during 2006-2007, analysing relationships between catches, depredation on hooked fish, cetacean sightings, acoustic records of cetacean presence and environmental variables. Data were provided by skippers of six vessels and by on-board observers for two vessels. The percentage of longline sets depredated by cetaceans was low (ranging from 1% to 9% of total sets per ship) but the proportion of fish damaged was high (up to 100%) when depredation occurred. Catches were related to the phase of the moon, cloud cover, sea surface temperature and water depth whereas cetacean sightings were primarily related to catches. In particular there was a positive association between Delphinus delphis sightings and catches of swordfish, and between Stenella frontalis sightings and mako catches. Acoustic detection was low when depredation by false killer whales occurred although high rates of clicks were detected when delphinids were sighted and false killer whales were by-caught. This may indicate that false killer whales are not echolocating when feeding on fish hooked on a longline.
AB - In the Atlantic, economic losses have been reported from shark, swordfish and tuna longline fisheries due to depredation by cetaceans. We examined interactions of odontocete cetaceans with commercial longliners operating in waters off Brazil and the Azores archipelago during 2006-2007, analysing relationships between catches, depredation on hooked fish, cetacean sightings, acoustic records of cetacean presence and environmental variables. Data were provided by skippers of six vessels and by on-board observers for two vessels. The percentage of longline sets depredated by cetaceans was low (ranging from 1% to 9% of total sets per ship) but the proportion of fish damaged was high (up to 100%) when depredation occurred. Catches were related to the phase of the moon, cloud cover, sea surface temperature and water depth whereas cetacean sightings were primarily related to catches. In particular there was a positive association between Delphinus delphis sightings and catches of swordfish, and between Stenella frontalis sightings and mako catches. Acoustic detection was low when depredation by false killer whales occurred although high rates of clicks were detected when delphinids were sighted and false killer whales were by-caught. This may indicate that false killer whales are not echolocating when feeding on fish hooked on a longline.
KW - cetaceans
KW - false killer whale
KW - longline fishery
KW - depredation
KW - hydrophones
KW - behaviour
KW - habitat modelling
KW - bottle-nosed dolphins
KW - ultrasonic telemetry
KW - pseudorca-crassidens
KW - pelagic longlines
KW - swordfish fishery
KW - sea-turtles
KW - T-pods
KW - tuna
KW - echolocation
KW - Southern
U2 - 10.1007/s10750-008-9501-2
DO - 10.1007/s10750-008-9501-2
M3 - Article
SN - 0018-8158
VL - 612
SP - 251
EP - 268
JO - Hydrobiologia
JF - Hydrobiologia
IS - 1
ER -