Cephalopods in the diet of marine mammals stranded or incidentally caught along southeastern and southern Brazil (21–34°S)

Santos, Roberta Aguiar dos; Haimovici, Manuel

doi:10.1016/s0165-7836(01)00234-x

Cited by 96 publications

(28 citation statements)

References 8 publications

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“…This might indicate that both delphinid species share the same habitat, but feed on different prey. However, other studies suggest that the trophic ecology of Delphinus delphis and Stenella frontalis is quite similar (Aguiar dos Santos & Haimovici, 2001).…”

Section: Discussionmentioning

confidence: 98%

Results of a short study of interactions of cetaceans and longline fisheries in Atlantic waters: environmental correlates of catches and depredation events

et al. 2008

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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 onboard 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.

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Section: Discussionmentioning

confidence: 98%

Results of a short study of interactions of cetaceans and longline fisheries in Atlantic waters: environmental correlates of catches and depredation events

et al. 2008

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“…The relatively gracile underslung mandibles contain up to 16 pairs of fang-like teeth (Handley, 1966;Ross, 1978;Caldwell and Caldwell, 1989) that are likely advantageous for retaining squid in the mouth. As in other potential suction feeding odontocetes, kogiids are primarily teuthophagous (Pinedo, 1987;Aguiar Dos Santos and Haimovici, 2001;Wang et al, 2002).…”

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confidence: 99%

Feeding kinematics ofKogiaandTursiops(Odontoceti:Cetacea): characterization of suction and ram feeding

Bloodworth

Marshall

2005

Journal of Experimental Biology

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SUMMARY The feeding kinematics of dwarf and pygmy sperm whales (Kogia simaand K. breviceps) and bottlenose dolphins Tursiops truncatuswere characterized and compared incorporating the Ram-Suction Index (RSI). Mean RSI data support a suction feeding strategy for Kogia(-0.67±0.29; mean ± s.d.) and a ram feeding strategy for Tursiops (0.94±0.11; mean ± s.d.). Tursiops displayed two ram-based feeding behaviours: open gape approach, where gape was at least 50% of maximum in the first video field, and closed gape approach, where gape increased near food items. Four feeding phases were identified in both odontocetes: preparatory, jaw opening, gular depression and jaw closing. The mean Kogia feeding cycle duration(470±139 ms) was significantly shorter (P<0.003) than all Tursiops groups (pooled: 863±337 ms; open gape approach:1211±207 ms; closed gape approach: 662±207 ms). Kogiamean maximum gape angle (39.8±18.9°), mean maximum opening and closing gape angle velocities (293±261 deg. s-1 and 223±121 deg. s-1, respectively) were significantly greater(P<0.005) than pooled Tursiops mean maximum gape angle(24.8±6.6°), mean maximum opening and closing gape angle velocities(84±56 deg. s-1 and 120±54 deg. s-1,respectively). Negative Kogia RSI values were correlated with increasing maximum gular depression and retraction, wide gape angle, and rapid opening gape angle velocity. Kinematic data support functional hypotheses that odontocetes generate suction by rapid depression of the hyoid and tongue.

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“…Killer whales feed on cephalopods elsewhere (e.g., Aguiar dos Santos & Haimovici, 2001;Berzin and Vladimirov, 1983;Hanson and Walker, 2014;Jonsgård and Lyshoel, 1970;Nishiwaki and Handa, 1958;Rice, 1968;Yamada et al, 2007). Cephalopods represented 89.6 -99.3% of prey by number in four killer whale specimens from across the Pacific examined by Hanson and Walker (2014); two of these individuals fed on mesopelagic squids.…”

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confidence: 99%

Movement and diving of killer whales ( Orcinus orca ) at a Southern Ocean archipelago

Reisinger

Keith

Andrews

et al. 2015

Journal of Experimental Marine Biology and Ecology

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Eleven satellite tags were deployed on 9 killer whales at the Prince Edwards Islands in the Southern Ocean. State-space switching models were used to generate position estimates from Argos location data, while two behavioural modes were estimated from the data. Individuals were tracked for 5.6-53.2 days, during which time they moved 416-4,470 km (mean 82.7 km day -1 ) but 69% of position estimates were within the 1000 m depth contour around the islands (<35 km from the tagging site). Killer whales showed restricted behaviour close to the islands, particularly inshore where they can effectively hunt seals and penguins, and at seamounts to the north of the islands.Generalized linear mixed effect models were used to explore the relationship between environmental variables and behavioural mode. The best model included depth, sea surface temperature, latitude, sea surface height anomaly and bottom slope, but killer whales did not clearly target features such as fronts and apparent mesoscale eddies. Killer whales showed restricted behaviour in shallow water, at high latitudes and low sea surface temperature -the conditions characterising the archipelago.Dive data from two individuals largely revealed shallow dives (7.5-50 m deep), but deeper dive bouts to around 368 m were also recorded. Dives were significantly deeper during the day and maximum dive depths were 767.5 and 499.5 m, respectively. This suggests that killer whales might also prey on vertically migrating cephalopods and perhaps Patagonian toothfish.Three individuals made rapid and directed long-distance movements northwards of the islands, the reasons for which are speculative.

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Cephalopods in the diet of marine mammals stranded or incidentally caught along southeastern and southern Brazil (21–34°S)

Cited by 96 publications

References 8 publications

Results of a short study of interactions of cetaceans and longline fisheries in Atlantic waters: environmental correlates of catches and depredation events

Results of a short study of interactions of cetaceans and longline fisheries in Atlantic waters: environmental correlates of catches and depredation events

Feeding kinematics ofKogiaandTursiops(Odontoceti:Cetacea): characterization of suction and ram feeding

Movement and diving of killer whales ( Orcinus orca ) at a Southern Ocean archipelago

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