Longlines

Menezes, Gui; Sigler, Michael F.

doi:10.1002/9781118332535.ch8

Cited by 3 publications

(5 citation statements)

References 50 publications

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“…Transects were randomly distributed in each seamount area and the number of sets by depth stratum was allocated proportional to its area size (Table 1). 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).…”

Section: Methodsmentioning

confidence: 99%

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%

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

et al. 2020

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“…In addition, midwater trawls are frequently used to catch pelagic fish and cephalopods in the water column. If predatory fishes are the main subject of a study, long lines are a reliable method to assess the diversity and fish stocks in a certain habitat (Menezes and Sigler, 2016). They are generally baited, which results in scavengers and predatory species being the main catch.…”

Section: Methods To Assess Deep-sea Biodiversitymentioning

confidence: 99%

“…They are generally baited, which results in scavengers and predatory species being the main catch. However, they are useful in areas where other sampling methods are inaccessible due to the bottom topography (Menezes and Sigler, 2016).…”

Section: Methods To Assess Deep-sea Biodiversitymentioning

confidence: 99%

Shedding Light on Deep-Sea Biodiversity—A Highly Vulnerable Habitat in the Face of Anthropogenic Change

Paulus

2021

Front. Mar. Sci.

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The deep sea is the most extensive habitat on our planet, and it supports surprisingly high biodiversity. With a multitude of different environments and conditions previously thought to be inhabitable, it is unclear how such high diversity was able to develop, but habitat heterogeneity and nutrient flux are certainly important factors to consider. In this review, the different methodologies used to examine biodiversity in the remote depths of the oceans are considered. In addition, the different environments in which biodiversity is studied are presented, and the various hypotheses on how high biodiversity is possible are examined. Unfortunately, this diversity is threatened by human impact similarly to shallow waters, and future endeavors such as deep-sea mineral extraction must be considered as a major threat to the environment. Many mysteries persist in the deep sea, but it is certain that threats such as overfishing, plastic pollution, and changes in ocean chemistry due to climate change are impacting even the most remote places in the oceans. It remains uncertain whether the deep sea is resilient toward anthropogenic disturbances, yet this is difficult to research on short timescales. There is little hope for areas in which exploitation, such as deep-sea mining, will be directly impacting the benthos and proper regulations are required to preserve biodiversity in the deep sea.

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“…These canyons can reach a depth of 2500-3000 m and connect to the Biscay Abyssal Plain below 4500 m in depth. Therefore, this area is considered inappropriate to conduct scientific trawling surveys, thus leading to the consideration that longline is the most appropriate gear to be used (Menezes & Sigler, 2016). One of the key benefits of longline is that it is a very efficient fishing gear for fish sampling, and it allows quantification of the catch and fishing effort in a replicable manner.…”

Section: Introductionmentioning

confidence: 99%

“…One of the key benefits of longline is that it is a very efficient fishing gear for fish sampling, and it allows quantification of the catch and fishing effort in a replicable manner. In this sense, successful longline surveys to assess the abundance and biodiversity of several demersal and deep-water fish species have been carried out in the Canary Islands, North-east Atlantic seamounts, Alaska, Greenland, Madeira and Azores (Connolly & Kelly, 1996; Uiblein et al ., 1996; Simonsen et al ., 2000; Clarke & Moore, 2002; ICES, 2005, 2008; Menezes et al ., 2006, 2009, 2015; Rodgveller et al ., 2008; Aranha et al ., 2009; Clausen & Rodgveller, 2013; Christiansen et al ., 2015; Biscoito et al ., 2017; Santos et al ., 2019).…”

Section: Introductionmentioning

confidence: 99%

Preliminary observations on abundance and distribution of fish fauna in a canyon of the Bay of Biscay (ICES Division 8c)

et al. 2021

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The changes in abundance and biodiversity of deep-sea fish fauna are described based on an annual deep-water longline survey with data collected during the period 2015–2019 in the Basque Country continental Slope (ICES Division 8c). The sampling scheme included hauls in four 400 m strata, from 650–2250 m deep. The DST sensors installed in the main line have allowed us to set an accurate soak time for each haul, and they were used to calculate fishing effort and CPUE by haul. The catchability of the fishing gear indicated that 15% of the total hooks deployed in the five-year period were able to fish, and that the bottom longline was very effective in fishing a wide number of different species in all depth ranges. The fishing gear caught 14 different species of sharks (13 deepwater and one pelagic), two chimaeras and nine teleosts. The abundance and biomass registered on the hooks attached to the bottom were between three and four times higher than in the floating sections, and the highest CPUE and biomass were recorded between 1051–1450 m, from 2015 to 2017, and in the 1451–1850 m strata, but they do not show any clear trend throughout the five years of the series.

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Longlines

Cited by 3 publications

References 50 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)

Shedding Light on Deep-Sea Biodiversity—A Highly Vulnerable Habitat in the Face of Anthropogenic Change

Preliminary observations on abundance and distribution of fish fauna in a canyon of the Bay of Biscay (ICES Division 8c)

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