Sustainability of capture of fish bycatch in the prawn trawling in northeastern Brazil

Abstract

The prawn fishery produces more discards than any other type of catch and captures a large quantity of immature individuals. This research aimed to assess the sustainability of capture of fish bycatch in prawn trawling. Each species was assessed according to two groups of criteria: (1) their relative vulnerability to capture by trawl and mortality due to this fishery (2) recovery capacity of the specie after a possible collapse of the population. Within each group, each species was ranked (1-3), being 1 the highest value, meaning the species is highly susceptible to capture or has a low resilience. A total of 8,894 individuals were caught, belonging to 28 families. The species with capture least sustainable were Stellifer rastrifer and Isopisthus parvipinnis. These latter species are highly susceptible since they are either benthic or demersal, and their diet may include benthic organism. Chirocentrodon bleekerianus and Anchoa tricolor were the most likely fishes to be sustainable since they are pelagic, they are least susceptible to capture by trawls, and also have a greater capacity to recover, as most individuals have bred before capture. Due to the fishery's multi-specific nature, it is difficult to implement mitigation measures for specific species. Thus, the creation of fishing exclusion zones should be considered as the most appropriate management measure.A pesca de arrasto de camarão produz mais descarte do que qualquer outra pescaria e captura uma grande quantidade de indivíduos imaturos. Esta pesquisa visa determinar a sustentabilidade da captura da ictiofauna acompanhante na pesca de arrasto de camarão. Cada espécie foi analisada de acordo com dois grupos de critérios: (1) vulnerabilidade à captura pela rede de arrasto e mortalidade ocasionada por esta pescaria; e (2) capacidade de recuperação da população para minimizar. Dentro de cada critério as espécies foram classificadas de 1 a 3, sendo 1 o valor mais alto, indicando que a espécie é altamente susceptível à captura ou tem baixa capacidade de recuperação. Um total de 8.894 indivíduos foram capturados, pertencendo a 28 famílias. As espécies com captura menos sustentável foram Stellifer rastrifer e Isopisthus parvipinnis. Estas espécies são altamente susceptíveis, pois são bentônicas ou demersais e suas dietas incluem organismos bentônicos. Chirocentrodon bleekerianus e Anchoa tricolor foram as espécies que apresentaram a captura mais sustentável. Por serem pelágicas, são menos susceptíveis à captura por arrastos de fundo, além disto, apresentaram uma grande capacidade de recuperação, pois a maior parte dos indivíduos capturados encontrava-se acima do seu tamanho de primeira maturação sexual. Devido à natureza multiespecífica da pescaria é difícil implementar medidas mitigatórias específicas. Assim, a criação de zona de exclusão de pesca deve ser considerada como a medida de manejo mais adequada.

DNA Barcoding for the Assessment of the Taxonomy and Conservation Status of the Fish Bycatch of the Northern Brazilian Shrimp Trawl Fishery

“…This further highlights the impact of trawling fisheries on the biodiversity of the Brazilian coast. Trawling is the most common shrimping method used in the region, which impacts most the fauna of sciaenids and haemulids, the families that make up a large part of the fish bycatch taken off the coast of Brazil (see Vianna and Almeida, 2005;Branco et al, 2015;Silva-Júnior et al, 2013Marceniuk et al, 2019). This pressure from shrimp trawling operations, combined with the overfishing of some of the commercially important species may lead to widespread ecological impacts and the decline of stocks.…”

Ecological and conservation aspects of bycatch fishes: An evaluation of shrimp fisheries impacts in Northeastern Brazil

“…The high catch of juveniles is characteristic of shrimp trawling. In Pernambuco, near to the study site , Silva Júnior et al (2013) observed that 64% of the individuals caught are below the size of first maturation (L 50 ). The low selectivity of the fishing gear (Branco and Verani, 2006) and in our case the very shallow fishing zone may contribute to high juvenile catches, due to the lower swimming capacity at this stage, when compared to the adult specimens.…”

“…This activity is focused on shallow waters and has great social-economic importance, since approximately 100,000 persons depend directly or indirectly of this fishery for their living (Santos et al, 2006). Previous studies focusing on the bycatch species in the northeast of Brazil (Silva-Júnior et al, 2013;Eduardo et al, 2019;Lira et al, in press) provided valuable biological and population information of a variety of species. However, many species still lack basic knowledge that is required for management and conservation actions, such as length-weight relationships and size at first gonadal maturity and also indicators of the ecological roles of the fish species, especially those related to the balancing of the marine food web which may influence the composition of this ecosystem (Elliott et al, 2007).…”

“…(* without information of LWRs parameters for Brazil; ** Without information of LWRs parameters for Northeastern Brazil); (female (F), male (M), unidentified (U), pooled sexes (P)). Paiva et al, 2008); 3- (Vasconcelos-Filho and Oliveira, 1999); 4- (Petermann and Schwingel, 2016); 5 - (Cervigón et al, 1992); 6- (Vasconcelos-Filho, 1979); 7- (Muto et al, 2014); 8- (Passos et al, 2013); 9- (Nizinski and Munroe, 2002); 10- (Bigelow et al, 1963); 11- (Silva Júnior at al., 2013); 12- (Giarrizzo et al, 2006); 13- (Vasconcelos-Filho and Oliveira, 2001); 14- (Ramos, 2006); 15- (Kullander and Ferraris, 2003); 16- (Bortoluzzi et al, 2006); 17- (Mai and Vieira, 2013); 18 - (Barreto et al, 2018); 19 - (Corrêa et al, 2005); 20- (Freire et al, 2009); 21- (Santos et al, 2011);22-(Muto et al, 2008); 23 - (Andrade, 2016);…”

Ichthyofauna in the Inner Continental Shelf Next to the Paranaguá Estuarine Complex, Southern Brazil

“…Key species are those that make up the community base and, when absent, result in a substantially different community (Mahon and Smith, 1989). The concept of key species can be applied in this study, where 37.2% of the total catch of individuals was from the family Sciaenidae; the high 9/13 representativeness of this family seems to be a common pattern in the sand-muddy bottom areas of the brazilian coast (Muto et al, 2000;Moraes et al, 2009;Silva Junior et al, 2013;Nóbrega et al, 2019). This predominance is common in other estuaries of the world and is due to the fact that this transition between marine/ euryhaline environments occurred several times throughout the evolutionary history of the family.…”