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SC/69A/CMP/09 Rev1
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Resource ID
19971
Access
Open
Document Number
SC/69A/CMP/09 Rev1
Full Title
Paralytic shellfish poisoning and mortality of Southern right whales (Eubalaena australis) in Golfo Nuevo, Península Valdés, Argentina in 2022
Author
Marcela Uhart, Mariano Sironi, Agustina Donini, Nora Montoya, Belen Mattera, Adrian Rodriguez, Ralph E.T. Vanstreels, Luciana Gallo, Norma Santinelli, Viviana Sastre
Authors Summary
A total of 28 adult (22 females) and 2 juvenile Southern right whales (SRW, Eubalaena australis) died acutely between 24 September - 11 October 2022, in Golfo Nuevo, Península Valdés, Argentina. Six whales were necropsied and found in good body condition with recent food intake and no evidence of trauma. The neurotoxin producing Pseudo-nitzschia australis diatom and Alexandrium catenella/tamarense complex dinoflagellates were identified in gut content from 4/5 whales. Tissues and fluids from 8 whales including stomach and intestinal content, liver, aqueous and vitreous humor of the eye, kidney, milk, urine, and blood were tested for biotoxins. Domoic acid was not detected. Paralytic Shellfish Toxins (PST) were found in 19/24 samples tested, from all whales. Saxitoxin was the most frequent toxin (n=14), followed by neosaxitoxin, and gonyautoxins 3 and 2. Evidence of toxin metabolism following ingestion was found. The highest toxicity levels (ug STX eq.g-1) were measured in intestinal content, blood, and feces. Whale mortality overlapped in time and space with a Harmful Algal Bloom (HAB) and unprecedented values of PST in shellfish and plankton in Golfo Nuevo. Adult females were the most affected group, coinciding with high energy demands from nursing newborn calves and urge to feed on spring plankton blooms. This is the largest known adult SRW mortality to date for the species. Although HABs are widespread along the Patagonian Shelf, their occurrence at Península Valdés raises concern for SRW conservation given increasing adult and juvenile mortality since 2019.
Publication Year
2023
Abstract
Revised 14-04-2023
A total of 28 adult (22 females) and 2 juvenile Southern right whales (SRW, Eubalaena australis) died acutely between 24 September - 11 October 2022, in Golfo Nuevo, Península Valdés, Argentina. Six whales were necropsied and found in good body condition with recent food intake and no evidence of trauma. The neurotoxin producing Pseudo-nitzschia australis diatom and Alexandrium catenella/tamarense complex dinoflagellates were identified in gut content from 4/5 whales. Tissues and fluids from 8 whales including stomach and intestinal content, liver, aqueous and vitreous humor of the eye, kidney, milk, urine, and blood were tested for biotoxins. Domoic acid was not detected. Paralytic Shellfish Toxins (PST) were found in 19/24 samples tested, from all whales. Saxitoxin was the most frequent toxin (n=14), followed by neosaxitoxin, and gonyautoxins 3 and 2. Evidence of toxin metabolism following ingestion was found. The highest toxicity levels (ug STX eq.g-1) were measured in intestinal content, blood, and feces. Whale mortality overlapped in time and space with a Harmful Algal Bloom (HAB) and unprecedented values of PST in shellfish and plankton in Golfo Nuevo. Adult females were the most affected group, coinciding with high energy demands from nursing newborn calves and urge to feed on spring plankton blooms. This is the largest known adult SRW mortality to date for the species. Although HABs are widespread along the Patagonian Shelf, their occurrence at Península Valdés raises concern for SRW conservation given increasing adult and juvenile mortality since 2019.