Azorean demersal longline survey abundance estimates: Procedures and variability

Pinho, Mário; Medeiros‐Leal, Wendell; Sigler, Michael F.; Santos, Régis; Novoa‐Pabon, Ana; Menezes, Gui; Silva, Hélder

doi:10.1016/j.rsma.2020.101443

Cited by 11 publications

(18 citation statements)

References 35 publications

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“…Fishing gear was very similar to the one used by the Azorean demersal fleet locally known as “stone‐buoy longline” (ICES, 2010; Menezes & Sigler, 2016). Relative abundance indices (mean catch rates multiplied by the corresponding area size) were computed by depth stratum and seamount area for each species collected during the ARQDAÇO (Pinho et al., 2020). Detailed information on survey design and abundance index estimation procedures are given by ICES (2010) and Pinho et al.…”

Section: Methodsmentioning

confidence: 99%

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Demersal fish assemblages on seamounts exploited by fishing in the Azores (NE Atlantic)

et al. 2020

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Seamount fish communities are susceptible to variations due to the oceanographic conditions and level of historical fishing effort. In the NE Atlantic, the Azores is considered an “oceanic seamount ecosystem area” because seamount concentration is high relative to other regions. Scientific information on seamounts in the Azores remains scarce and demersal fishery occurs mostly without any knowledge to endorse sustainable harvest strategies. To make available an important baseline information on dynamics of demersal fish populations inhabiting commercially exploited seamounts, the present study has as specific objectives to (a) describe the taxonomic composition of demersal fish assemblages on underwater mountains, (b) examine whether assemblages vary spatial and temporally, and (c) investigate what drives distributional patterns of species in terms of abundance and size composition. For this, three Azorean seamounts (Açores, Princesa Alice and Mar da Prata) exploited by bottom fishing were selected as case study areas. Data were obtained from scientific surveys and commercial fishery over the past c. 25 years. A total of 84 species from 45 families were identified. Sebastidae, Moridae, Sparidae and Centrophoridae were the most abundant families, mainly represented by Helicolenus dactylopterus, Mora moro, Pagellus bogaraveo and Deania profundorum, respectively. Fish assemblages were more distinguishable spatially than temporally. Depth was identified as the main factor responsible for these differences. The higher occurrence of shallow and intermediate (i.e., up to 600 m) habitats in Princesa Alice and Açores seems to favor the occurrence of a greater number of species and higher abundances in comparison to Mar da Prata. Phycis phycis, Pontinus kuhlii, H. dactylopterus, P. bogaraveo, Conger conger and M. moro were the species which primarily contributed to dissimilarities in assemblage structure among sample groups. Abundance indices and fish sizes showed a decreasing trend for many of these species, especially for those with sedentary behaviour inhabiting historically highly exploited seamount areas. These results highlighted the vulnerability of demersal fishes to the expansion of fishing effort in the offshore seamount areas. Spatial management of seamounts should be a priority being fish conservation balanced with strategies that support sustainable fisheries.

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Section: Methodsmentioning

confidence: 99%

“…Detailed information on survey design and abundance index estimation procedures are given by ICES (2010) and Pinho et al. (2020).…”

Section: Methodsmentioning

confidence: 99%

Demersal fish assemblages on seamounts exploited by fishing in the Azores (NE Atlantic)

et al. 2020

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“…Survey gear was similar to locally known gear called the "stone/buoy" longline used by the Azorean commercial fishery (Pinho et al 2020). Relative abundance indices (mean catch per unit of effort weighted by the corresponding area size) were estimated by depth strata and statistical area.…”

Section: Methodsmentioning

confidence: 99%

“…The European conger Conger conger (L.) is the largest species of the Congridae family distributed in the Eastern Atlantic (Norway and Iceland to Senegal, including the Macaronesian archipelagos) and the Mediterranean and Black seas (Froese & Pauly, 2019). This species feeds on fish, Cephalopoda and Crustacea, and inhabits rocky and sandy bottoms at depths down to 4000 m (Cau & Manconi, 1984; Xavier et al 2010), but it is usually found down to 600 m (Pinho et al 2020; Santos et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Population structure of the European conger Conger conger from the mid‐North Atlantic Ocean inferred from bathymetric distribution, length composition and movement patterns analyses

Medeiros‐Leal

Santos

Novoa‐Pabon

et al. 2021

Fisheries Management Eco

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Information about the population structure of Conger conger (L.) is scarce, being a limiting factor for fisheries assessment. To make available important baseline information and to test the hypothesis that the population in the mid‐North Atlantic (Azores region) represents a fishery management unit, fishery‐dependent and survey data relating to bathymetric distribution, length composition and movement patterns were examined. Fishing impacts were also evaluated using abundance and size trends over the last 25 years. The greatest abundance was in depths between 300 and 600 m. Sizes ranged from 14 to 260 cm, with larger individuals around seamounts. Tagging data showed a strong sedentary behaviour. Results combined with previous genetic and otolith studies indicated the stock in the Azores may represent a self‐contained population. Abundance and size trends were stable, but the species is considered vulnerable to overfishing due to its biological characteristics. Monitoring and adequate rational resource management are of utmost importance.

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“…Fork length (L F ), weight, and sex were recorded for each fish. Detailed information on survey design and abundance index estimation procedures is given by Pinho et al [20].…”

Section: Datasetsmentioning

confidence: 99%

Contributions to Management Strategies in the NE Atlantic Regarding the Life History and Population Structure of a Key Deep-Sea Fish (Mora Moro)

Santos

Medeiros‐Leal

Crespo

et al. 2021

Biology

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With the commercial fishery expansion to deeper waters, some vulnerable deep-sea species have been increasingly captured. To reduce the fishing impacts on these species, exploitation and management must be based on detailed and precise information about their biology. The common mora Mora moro has become the main deep-sea species caught by longliners in the Northeast Atlantic at depths between 600 and 1200 m. In the Azores, landings have more than doubled from the early 2000s to recent years. Despite its growing importance, its life history and population structure are poorly understood, and the current stock status has not been assessed. To better determine its distribution, biology, and long-term changes in abundance and size composition, this study analyzed a fishery-dependent and survey time series from the Azores. M. moro was found on mud and rock bottoms at depths below 300 m. A larger–deeper trend was observed, and females were larger and more abundant than males. The reproductive season took place from August to February. Abundance indices and mean sizes in the catch were marked by changes in fishing fleet operational behavior. M. moro is considered vulnerable to overfishing because it exhibits a long life span, a large size, slow growth, and a low natural mortality.

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Azorean demersal longline survey abundance estimates: Procedures and variability

Cited by 11 publications

References 35 publications

Demersal fish assemblages on seamounts exploited by fishing in the Azores (NE Atlantic)

Demersal fish assemblages on seamounts exploited by fishing in the Azores (NE Atlantic)

Population structure of the European conger Conger conger from the mid‐North Atlantic Ocean inferred from bathymetric distribution, length composition and movement patterns analyses

Contributions to Management Strategies in the NE Atlantic Regarding the Life History and Population Structure of a Key Deep-Sea Fish (Mora Moro)

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