Length-weight relationships of four finfish commercial species from the southern Gulf of Mexico

The relationship between total length and total weight (LWR) of four commercial species of finfish captured in the southern Gulf of Mexico (Lachnolaimus maximus, Ocyurus chrysurus, Mycteroperca bonaci, and Mycteroperca microlepis) was estimated. Two of these species are captured in the region by the small-scale fleet, while the other two are targeted by small-scale and semi-industrial fleets using harpoons, handlines, and long-lines. For the assessment, the organisms were sampled at the landing decks in the study area in two periods: 1996-1999 (semi-industrial fleet) and from April 2017 to May 2018 (small-scale fleet). A total of 2780 individuals were sampled which 2775 individuals were used to obtain LWR functions. The four species showed negative allometric growth with b < 3 for the 2017-2018 period, two species showed positive allometric growth with b > 3 for the 1996-1999 period. This type of information is an important input for the stock assessment of these species that support important fisheries in the zone and are under high fishing pressure levels.

Filling gaps: fishing, genetics, and conservation of groupers, especially the comb grouper (badejo) (Mycteroperca acutirostris), in SE Brazil (2013-2020)

There are large gaps in our knowledge of the biology of important fish consumed by people in tropical countries, which makes conservation difficult. Small-scale fisheries are difficult to study and regulate, especially in countries with no systematic species monitoring. It is even more difficult to estimate the influence of these fisheries on vulnerable fish species and to diagnose possible damage to local fish populations. In this study, 490 individuals of badejo, or comb grouper (Mycteropeca acutirostris), were observed at the Posto 6 fishery in Copacabana, Rio de Janeiro, for the periods of 2013-2014 and 2018-2020. A pattern of decreasing catches was observed for comb grouper. Therefore, provided that the fishing gear and the number of fish have remained the same, the apparent decrease in comb grouper needs to be further investigated. The results provide information regarding the reproduction of comb grouper, with major spawning season around spring (September-December) and additional spawning during April in SE Brazil. Samples from 96 groupers along the coast of Brazil were obtained, and genetic analyses were conducted. The genetic information obtained for grouper species enabled us to determine the relative genetic proximity of M. acutirostris and Mycteroperca bonaci and to obtain information that can be useful for aquaculture and conservation.

Length-based indicators for the management of sport fishery in Yucatan, Mexico

Sportfishing is an activity of increasing popularity that involves a large number of users and high levels of fishing effort. In Yucatan, most of the target species in sport fishing are the same as those of commercial fisheries. However, there is no record of fishing effort or catch volumes. Thus the impact of sport fishing on these populations is unknown. This study analyzes the catches made by users of sport fisheries of nine species (Epinephelus morio, Haemulon plumieri, Seriola dumerili, Lutjanus synagris, Ocyurus chrysurus, Calamus bajonado, Sphyraena barracuda, S. guachancho and Mycteroperca bonaci) through length-based indicators. Samples of species’ sizes were obtained from the catches made during 10 fishing tournaments held in Yucatan's three-port towns (Sisal, Yucalpeten, and Telchac) between 2015 and 2016. The catch variables that were evaluated included: the number of mature individuals Pmat, optimal length Popt, and the number of mega-spawners Pmega. Length measures were derived from 1,252 individuals. Only H. plumieri, L. synagris, and S. guachancho exhibited sustainable indicator values, while E. morio and C. bajonado demonstrated extremely low values. In most species, sport fishing affects a high proportion of juveniles. The results suggest that sportfishing contributes to the fishing pressure of a species and commercial fishing, due to the capture of juveniles of economically important fish. It is essential to establish a systematic monitoring method of such activities and increase the priority level of the evaluation and management of this fishery.

DISTRIBUIÇÃO E ABUNDÂNCIA DE ALGUNS PEIXES BENTÔNICOS NA ÁREA DE ABROLHOS (BRASIL)

A área de Abrolhos é uma importante zona de pesca de peixes bentônicos habitantes de fundos rochosos, onde as principaisespécies capturadas, em ordem decrescente de importância, são as seguintes: garoupa =Epinephelus guaza (Linnaeus, 1758),badejo = Mycteroperca bonaci (Poey, 1860) e cioba = Ocyurus chrysurus (Bloch, 1791). Em conjunto, estas espécies contribuíram com 73,3% do total da produção, com a média anual de 696.562kg (1986-1989). Estes são os peixes dominantes na biocenose, com 31,7%, 25,5% e 16,1% da biomassa, respectivamente. As maiores produções destes peixes ocorreram no terceiro trimestre e as menores no quarto trimestre. O índice de abundância geral (kg/anzol-dia) foi de 2,03, com valores de0,64 para a garoupa, 0,52 para o badejo e 0,33 para a cioba. O esforço de pesca é bastante concentrado, com 88,3% deste aplicados numa sub-área equivalente a 20,1% da área total, onde se registrou a maior parte da produção (87,1 %). Em relação às espécies dominantes, nesta sub-área foram efetuadas 83,7% das capturas da garoupa, 87,7% das capturas do badejo e 92,1% das capturas da cioba. A garoupa e o badejo ocorrem em toda a plataforma continental e a cioba até BOm de profundidade, com a produção se concentrando na faixa de 31-60m, nas seguintes proporções: 90,8%, 89,9% e 92,7%, respectivamente.

Feeding ecology of two sympatric species of large-sized groupers (Perciformes: Epinephelidae) on Southwestern Atlantic coralline reefs

ABSTRACT Red and black groupers are large-bodied opportunistic ambush predators commonly found in Southwestern Atlantic tropical reefs. We investigated the diet of both species in order to detail ontogenetic, spatial and temporal trends, and to assess the extent of overlap in resource use between these two sympatric predators on the Abrolhos Bank, Brazil. Decapods and fishes were the main food items of Epinephelus morio while fishes were the main prey of Mycteroperca bonaci. Both diets were significantly influenced by body size and habitat, but only smaller individuals of E. morio feed almost exclusively on crustaceans. While the two groupers rely on many of the same prey types, coexistence may be facilitated by E. morio feeding more heavily on crustaceans, particularly the blackpoint sculling crab Cronius ruber, while black grouper take comparatively few crustaceans but lots of fish prey. Predators like red and black groupers could trigger indirect effects in the community and influence a large range of ecological processes, such as linkages between top and intermediate predators, and intermediate predators and their resources.

Indirect signals of spawning aggregations of three commercial reef fish species on the continental shelf of Bahia, east coast of Brazil

Lutjanus analis (Mutton snapper), Lutjanus jocu(Dog snapper) and Mycteroperca bonaci (Black grouper) are reef fishes of high commercial value, and are among the principal exploited reef resources on the eastern and northeastern coast of Brazil. These species share the habit of forming transient spawning aggregations, predictable in time and space, which leaves them particularly vulnerable. The present study aimed to obtain indirect indicators of periods and places of spawning aggregations for these species, based on the exploratory analysis of available data on commercial catches and fishing efforts in Southern Bahia. Line fishery landings data were monitored in 12 locations in the region, and catch records of Mutton snapper (1320 landings), Dog snapper (654) and Black grouper (1162) were analyzed. A strategy was developed for exploratory analysis of monthly CPUE variation and individual distribution of CPUE per trip. The results showed the occurrence of aggregations in 26 specific sites, with values of relative abundance far above the annual mean, during spring/summer and autumn/winter. The occurrence of these anomalous catches was validated with the fishermen responsible for respective fishing trips. Additional studies are needed to confirm spawning activity at these sites. Analysis of inter-annual variation suggests a decreasing trend in relative abundance of Black grouper and Mutton snapper, possibly associated with unregulated fishing of spawning aggregations.

Metazoan parasite infracommunities of Mycteroperca bonaci (Poey, 1960) (Pisces: Epinephelidae) in reef and coastal environments off the coast of Yucatán, México

The black grouper Mycteroperca bonaci is a commercially important fish off the coast of Yucatan, Mexico. To investigate possible differences between parasite communities in two different environments, 60 fish were collected from two areas during 2010 and 2011 and examined for parasites. The fish were classified into two age groups, in each of which the parameters of parasitic infection - prevalence, abundance and intensity - were determined. Parasite faunas were further described at the infracommunity level. Using both univariate (PERMANOVA) and multivariate statistical methods, the values of richness, abundance, diversity and Brillouin evenness as well as the Index values of Bray-Curtis and Jaccard for similarity were calculated and compared. The results of these tests and of CAP discriminant analyses at the two sites showed the existence of two distinct parasite communities. The parasite taxa mainly responsible for the differences were the digeneans Dollfustrema sp., Prosorhynchus spp., Lepidapedoides epinepheli and Hamacreadium mutabile, and the nematode Philometra salgadoi. The potential for some of these parasites to be used as biological tags for stock identification of M. bonaci is discussed.