Marine mammal bycatch by the industrial bottom trawl fishery at the Rio de la Plata Estuary and the adjacent Atlantic Ocean

Trecu, Valentina Franco; Szephegyi, María; Doño, Florencia; Forselledo, Rodrigo; Reyes, Federico; Passadore, Cecilia; Crespo, Enrique A.; Inchausti, Pablo

doi:10.3856/vol47-issue1-fulltext-10

Cited by 21 publications

(10 citation statements)

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“…Marine primary productivity is a major determinant of otariid pup growth and survival worldwide (Lunn et al 1994, Reid and Forcada 2005, Soto et al 2004, and populations of the same species inhabiting areas of contrasting primary productivity are expected to differ in pup production. Females breeding at Isla de Lobos (Uruguay) prey on large demersal fishes (Franco-Trecu et al 2013) on the continental shelf within a few kilometres of the rookery (Franco-Trecu et al 2019, Rodriguez et al 2013). These foraging grounds are adjacent to the highly productive plume of Río de la Plata (Acha et al 2008, Fig.…”

Section: Discussionmentioning

confidence: 99%

Relationship between the female attendance pattern and pup growth rate in the South American sea lion (Carnivora)

Drago

Cardona

Franco‐Trecu

et al. 2021

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Changes in the duration and frequency of foraging trips by female otariids may result in changes in the duration and frequency of lactation bouts and hence influence pup growth rate, unless females modify milk energy density and/or the total amount of milk delivered depending on the trip duration. To test this hypothesis on South American sea lions, we measured two attendance pattern components (foraging trip and haul-out duration) and three diving behaviour components of nursing females (dive time, bottom time and number of dives per h) at two different rookeries in Uruguay and Argentina, the composition and energy density of their milk, and the growth rate of their pups. Female foraging trip and haul-out durations depended on pup sex and weight, whereas milk energy density depended on female body mass and foraging trip durations. By contrast, the three dive variables were independent of female body mass or pup sex. Pup growth was also independent of the foraging trip and haul-out duration, with pup sex as the only significant variable. This suggests that individual differences in female foraging behaviour play a minor role in determining pup growth rates during the first three weeks after birth.

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Section: Discussionmentioning

confidence: 99%

Relationship between the female attendance pattern and pup growth rate in the South American sea lion (Carnivora)

Drago

Cardona

Franco‐Trecu

et al. 2021

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“…In recent decades, special attention has been given to the effects that fishing activities may have on species that are not their objective and on the actions that can be taken to avoid or at least prevent or mitigate their capture (Dietrich & Melvin, 2004). In southern waters, the main focus has been on studies on the incidental mortality of seabirds and the interaction with marine mammals (e.g., killer whales Orcinus orca, sperm whales Physeter macrocephalus, sealions) produced by longline deep-sea cod (Dissostichus eleginoides) fishing (e.g., González et al, 2012;Suazo et al, 2014;Franco-Trecu et al, 2019). Likewise, these investigations were extended regarding the occurrence of interactions when a trawling gear is used (e.g., Williams & Capdeville, 1996;Weimerskirch et al, 2000;Roe, 2005;Sullivan et al, 2006).…”

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confidence: 99%

Incidental catch of marine organisms registered in the Chilean Antarctic krill fishery, years 2012-2016

Arana

Rolleri²

2020

Lat. Am. J. Aquat. Res.

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Krill (Euphausia superba) catch is currently the most relevant fishery industry in Antarctic waters. This resource is a keystone species in the Antarctic food web, sustaining the contribution to the trophic ecology of many invertebrate and vertebrate species. To catch krill, part of the fleet in this fishery uses large mid-water nets that also retain a diversity of other organisms like plankton, meroplankton, and fish species as bycatch. Therefore, it is necessary to understand and evaluate the magnitude of this incidental catch, as well as the potential interactions between krill fishing gear with seabirds and mammals. To estimate the composition and extent of bycatch for this fishery included 784 samples of 25 kg and an equal number of 1 kg sub-samples obtained from Antarctic krill catches in Subarea 48, between years 2012 and 2016. A total of 15 fish species were identified along with the record of five other taxa and other unidentified specimens. The most relevant fish species bycaught by weight were mackerel icefish Champsocephalus gunnari, South Georgia icefish Pseudochaenichthys georgianus, and painted notie Lepidonotothen larseni. Additionally, 20 interactions with seabirds and nine interactions with Antarctic fur seals (Arctocephalus gazella) were registered. In the five years of operations, only three seabirds died, and only two individuals of A. gazelle caught by the net were killed.

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“…Midwater or surface trawl fisheries will sometimes have high marine mammal bycatch, depending on the gear, with larger openings and higher trawl speeds increasing risk; for this reason, some pair-trawl configurations have had particularly high bycatch and bycatch mortality rates (e.g., De Boer et al, 2012). Some bottom (demersal) trawl gear can have relatively high risk to marine mammal species that forage on or near the sea floor (e.g., Franco-Trecu et al, 2019).…”

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Best Practices for Assessing and Managing Bycatch of Marine Mammals

et al. 2021

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Bycatch in marine fisheries is the leading source of human-caused mortality for marine mammals, has contributed to substantial declines of many marine mammal populations and species, and the extinction of at least one. Schemes for evaluating marine mammal bycatch largely rely on estimates of abundance and bycatch, which are needed for calculating biological reference points and for determining conservation status. However, obtaining these estimates is resource intensive and takes careful long-term planning. The need for assessments of marine mammal bycatch in fisheries is expected to increase worldwide due to the recently implemented Import Provisions of the United States Marine Mammal Protection Act. Managers and other stakeholders need reliable, standardized methods for collecting data to estimate abundance and bycatch rates. In some cases, managers will be starting with little or no data and no system in place to collect data. We outline a comprehensive framework for managing bycatch of marine mammals. We describe and provide guidance on (1) planning for an assessment of bycatch, (2) collecting appropriate data (e.g., abundance and bycatch estimates), (3) assessing bycatch and calculating reference points, and (4) using the results of the assessment to guide marine mammal bycatch reduction. We also provide a brief overview of available mitigation techniques to reduce marine mammal bycatch in various fisheries. This paper provides information for scientists and resource managers in the hope that it will lead to new or improved programs for assessing marine mammal bycatch, establishing best practices, and enhancing marine mammal conservation globally.

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Marine mammal bycatch by the industrial bottom trawl fishery at the Rio de la Plata Estuary and the adjacent Atlantic Ocean

Cited by 21 publications

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Relationship between the female attendance pattern and pup growth rate in the South American sea lion (Carnivora)

Relationship between the female attendance pattern and pup growth rate in the South American sea lion (Carnivora)

Incidental catch of marine organisms registered in the Chilean Antarctic krill fishery, years 2012-2016

Best Practices for Assessing and Managing Bycatch of Marine Mammals

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