Escalle, L.,Capietto, A.,Chavance, P.,Dubroca, L.,Delgado De Molina, A.,Murua, H.,Gaertner, D.,Romanov, E.,Spitz, J.,Kiszka, J. J.,Floch, L.,Damiano, A.,Merigot, B.
Cetaceans and tuna purse seine fisheries in the Atlantic and Indian Oceans: interactions but few mortalities Journal Article
In: Marine Ecology Progress Series, vol. 522, no. 370, pp. 255-268, 2015.
Abstract | Links | BibTeX | Tags: Atlantic, Bycatch, cetaceans, Humpback Whale, Indian Ocean, megaptera novaeangliae, purse-Seine, tuna fishery
@article{,
title = {Cetaceans and tuna purse seine fisheries in the Atlantic and Indian Oceans: interactions but few mortalities},
author = {Escalle, L.,Capietto, A.,Chavance, P.,Dubroca, L.,Delgado De Molina, A.,Murua, H.,Gaertner, D.,Romanov, E.,Spitz, J.,Kiszka, J. J.,Floch, L.,Damiano, A.,Merigot, B.},
url = {http://www.int-res.com/abstracts/meps/v522/p255-268/},
year = {2015},
date = {2015-01-01},
journal = {Marine Ecology Progress Series},
volume = {522},
number = {370},
pages = {255-268},
abstract = {ABSTRACT: Fisheries bycatch is considered to be one of the most significant causes of mortality for many marine species, including vulnerable megafauna. In the open ocean, tuna purse seiners are known to use several cetacean species to detect tuna schools. This exposes the cetaceans to encirclement which can lead to incidental injury or death. While interactions between fishers and cetaceans have been well documented in the eastern tropical Pacific Ocean, little is known about these interactions and potential mortalities in the tropical Atlantic and Indian Oceans. Here, we provide the first quantification of these interactions in both oceans by analyzing a large database of captain’s logbooks (1980 to 2011) and observations collected by onboard scientific observers (1995 to 2011). Distribution maps of sightings per unit effort highlighted main areas of relatively high co-occurrence: east of the Seychelles (December to March), the Mozambique Channel (April to May) and the offshore waters of Gabon (April to September). The percentage of cetacean-associated fishing sets was around 3% in both oceans and datasets whereas 0.6% of sets had cetaceans encircled. Of the 194 cetaceans encircled in a purse seine net (122 baleen whales, 72 delphinids), immediate apparent survival rates were high (Atlantic: 92%, Indian: 100%). Among recorded mortalities, 8 involved pantropical spotted dolphins \textit{Stenella attenuata} and 3 involved humpback whales \textit{Megaptera novaeangliae}. These high survival rates suggest that setting nets close to cetaceans has a low immediate apparent impact on the species involved. Our findings will contribute to the development of an ecosystem approach to managing fisheries and accurate cetacean conservation measures.},
keywords = {Atlantic, Bycatch, cetaceans, Humpback Whale, Indian Ocean, megaptera novaeangliae, purse-Seine, tuna fishery},
pubstate = {published},
tppubtype = {article}
}
ABSTRACT: Fisheries bycatch is considered to be one of the most significant causes of mortality for many marine species, including vulnerable megafauna. In the open ocean, tuna purse seiners are known to use several cetacean species to detect tuna schools. This exposes the cetaceans to encirclement which can lead to incidental injury or death. While interactions between fishers and cetaceans have been well documented in the eastern tropical Pacific Ocean, little is known about these interactions and potential mortalities in the tropical Atlantic and Indian Oceans. Here, we provide the first quantification of these interactions in both oceans by analyzing a large database of captain’s logbooks (1980 to 2011) and observations collected by onboard scientific observers (1995 to 2011). Distribution maps of sightings per unit effort highlighted main areas of relatively high co-occurrence: east of the Seychelles (December to March), the Mozambique Channel (April to May) and the offshore waters of Gabon (April to September). The percentage of cetacean-associated fishing sets was around 3% in both oceans and datasets whereas 0.6% of sets had cetaceans encircled. Of the 194 cetaceans encircled in a purse seine net (122 baleen whales, 72 delphinids), immediate apparent survival rates were high (Atlantic: 92%, Indian: 100%). Among recorded mortalities, 8 involved pantropical spotted dolphins Stenella attenuata and 3 involved humpback whales Megaptera novaeangliae. These high survival rates suggest that setting nets close to cetaceans has a low immediate apparent impact on the species involved. Our findings will contribute to the development of an ecosystem approach to managing fisheries and accurate cetacean conservation measures.
Romanov, Evgeny V
Bycatch in the tuna purse-seine fisheries of the western Indian Ocean Journal Article
In: Fishery Bulletin, vol. 100, no. 455, pp. 90-105, 2002, ISBN: 0090-0656.
Abstract | BibTeX | Tags: balaenoptera, Bryde’s whale, Bycatch, Indian Ocean, purse-Seine, tuna fishery
@article{,
title = {Bycatch in the tuna purse-seine fisheries of the western Indian Ocean},
author = {Romanov, Evgeny V},
issn = {0090-0656},
year = {2002},
date = {2002-01-01},
journal = {Fishery Bulletin},
volume = {100},
number = {455},
pages = {90-105},
abstract = {Bycatch taken by the tuna purse-seine fishery from the Indian Ocean pelagic ecosystem was estimated from data collected by scientific observers aboard Soviet purse seiners in the western Indian Ocean (WIO) during 1986–92. A total of 494 sets on free-swimming schools, whale-shark-associated schools, whale-associated schools, and log-associated schools were analyzed. More than 40 fish species and other marine animals were recorded. Among them only two species, yellow-fin and skipjack tunas, were target species. Average levels of bycatch were 0.518 metric tons (t) per set, and 27.1 t per 1000 t of target species. The total annual purse-seine catch of yellowfin and skipjack tunas by principal fishing nations in the WIO during 1985–94 was 118,000–277,000 t. Nonrecorded annual bycatch for this period was estimated at 944–2270 t of pelagic oceanic sharks, 720–1877 t of rainbow runners, 705–1836 t of dolphinfishes, 507–1322 t of triggerfishes, 113–294 t of wahoo, 104–251 t of billfishes, 53–112 t of mobulas and mantas, 35–89 t of mackerel scad, 9–24 t of barracudas, and 67–174 t of other fishes. In addition, turtle bycatch and whale mortalities may have occurred. Because the bycatches were not recorded by some purse-seine vessels, it was not possible to assess the full impact of the fisheries on the pelagic ecosystem of the Indian Ocean. The first step to solving this problem is for the Indian Ocean Tuna Commission to establish a pro-gram in which scientific observers are placed on board tuna purse-seine and longline vessels fishing in the WIO.},
keywords = {balaenoptera, Bryde’s whale, Bycatch, Indian Ocean, purse-Seine, tuna fishery},
pubstate = {published},
tppubtype = {article}
}
Bycatch taken by the tuna purse-seine fishery from the Indian Ocean pelagic ecosystem was estimated from data collected by scientific observers aboard Soviet purse seiners in the western Indian Ocean (WIO) during 1986–92. A total of 494 sets on free-swimming schools, whale-shark-associated schools, whale-associated schools, and log-associated schools were analyzed. More than 40 fish species and other marine animals were recorded. Among them only two species, yellow-fin and skipjack tunas, were target species. Average levels of bycatch were 0.518 metric tons (t) per set, and 27.1 t per 1000 t of target species. The total annual purse-seine catch of yellowfin and skipjack tunas by principal fishing nations in the WIO during 1985–94 was 118,000–277,000 t. Nonrecorded annual bycatch for this period was estimated at 944–2270 t of pelagic oceanic sharks, 720–1877 t of rainbow runners, 705–1836 t of dolphinfishes, 507–1322 t of triggerfishes, 113–294 t of wahoo, 104–251 t of billfishes, 53–112 t of mobulas and mantas, 35–89 t of mackerel scad, 9–24 t of barracudas, and 67–174 t of other fishes. In addition, turtle bycatch and whale mortalities may have occurred. Because the bycatches were not recorded by some purse-seine vessels, it was not possible to assess the full impact of the fisheries on the pelagic ecosystem of the Indian Ocean. The first step to solving this problem is for the Indian Ocean Tuna Commission to establish a pro-gram in which scientific observers are placed on board tuna purse-seine and longline vessels fishing in the WIO.