72 research outputs found
Experiential-Informed Data Reconstruction for Fishery Sustainability and Policies in the Azores
Fishery analysis is critical in maintaining the long-term sustainability of
species and the livelihoods of millions of people who depend on fishing for
food and income. The fishing gear, or metier, is a key factor significantly
impacting marine habitats, selectively targeting species and fish sizes.
Analysis of commercial catches or landings by metier in fishery stock
assessment and management is crucial, providing robust estimates of fishing
efforts and their impact on marine ecosystems. In this paper, we focus on a
unique data set from the Azores' fishing data collection programs between 2010
and 2017, where little information on metiers is available and sparse
throughout our timeline. Our main objective is to tackle the task of data set
reconstruction, leveraging domain knowledge and machine learning methods to
retrieve or associate metier-related information to each fish landing. We
empirically validate the feasibility of this task using a diverse set of
modeling approaches and demonstrate how it provides new insights into different
fisheries' behavior and the impact of metiers over time, which are essential
for future fish population assessments, management, and conservation efforts
Migrações na fase pelágica do Cherne, Polyprion americanus (Schneider, 1801), evidenciadas por marcação e recaptura
Vários chernes juvenis, Polyprion americanus (Schneider. 1801) foram capturados à superfície da água e marcados em vários locais próximos das ilhas do Grupo Central dos Açores. Um dos exemplares foi recapturado 3 meses depois ter sido marcado, a 217 km do local onde tinha sido libertado e a uma profundidade de 254 m. A recaptura deste espécime indica que o cherne passa para uma vida demersal quando atinge um comprimento total de cerca de 50 cm.ABSTRACT: Pelagic juvenile wreckfish, Polyprion americanus (Schneider, 1801) were tagged in the surface waters around the Central Group of the Azores. One wreckfish was recaptured three months after tagging, and 217 km from its release point. It had settled to the bottom in 254 m of water. The recapture of this specimen suggests that wreckfish take up a demersal life at a total length of about 50 cm
Dynamics of Fisheries in the Azores Islands: A Network Analysis Approach
In the context of the global seafood industry, the Azores archipelago
(Portugal) plays a pivotal role due to its vast maritime domain. This study
employs complex network analysis techniques to investigate the dynamics of
Azores fisheries, using time series data converted into networks. We uncover
associations between Tunas and specific islands, consistent links among fish
classifications, and identify other pivotal nodes within the fishing network.
Remarkably, nodes with high degrees and a local clustering coefficient of one
provide crucial insights into the fishing ecosystem. This study highlights the
value of network analysis for understanding fisheries complexities and offers
insights into sustainable management and the preservation of marine ecosystems.
It also emphasizes the urgency for ongoing research and data collection to
enrich our understanding of this multifaceted domain
Dietas da abrótea (Phycis phycis) e do congro (Conger conger) dos Açores durante a primavera de 1996 e 1997
The forkbeard, Phycis phycis, and conger eel, Conger conger, are two coastal species, with a wide bathymetric and geographical distribution. The longline fleet of the Azores catches these two important commercial species. Few studies on their diet composition were found in literature. Data were collected during the demersal cruise surveys that took place aboard
the R/V “Arquipélago” during the spring of 1996 and 1997. Stomachs of 53 forkbeards and
95 conger eels were examined to define their diets. Both species fed primarily on fishes,
mainly on two benthopelagic species (Capros aper and Macroramphosus scolopax).
However, the relative importance of fish was higher for conger eel than for forkbeard,
which fed secondarily on decapods. Prey composition of the diet did not vary between
sexes, predator size or areas. However, some differences were found on diet composition
between depth strata. Prey composition indicates that both predators have the ability to feed near the bottom on benthic prey or in the water column on benthopelagic species
Primeiro registo do tubarão-anão, Squaliolus laticaudus (Smith & Radcliffe, 1912) nos Açores, estendendo a sua distribuição ocidental no Atlântico Nordeste
A presente nota documenta a primeira observação do tubarão-anão, Squaliolus laticaudus (Smith & Radcliffe, 1912), nos Açores, estendendo a sua distribuição ocidental no Atlântico Nordeste até ao arquipélago. A ocorrência da espécie nos arquipélagos macaronésicos é igualmente discutida.ABSTRACT: This paper reports the first observation of the spined pygmy shark, Squaliolus laticaudus, from the Azores, extending its westernmost distribution in the North-eastern Atlantic as far as this archipelago. The occurrence of this species in the Macaronesian archipelagos is also discussed
Staining techniques for ageing tope shark, Galeorhinus galeus (Linnaeus, 1758), from the Azores : a comparison based on precision analysis.
A vertebrae sample of tope shark, Galeorhinus galeus (Linnaeus, 1758), stratified by sizeclasses,was used to test between different staining techniques of enhancing vertebral growth ring visibility. Four techniques were tested: alizarin red, silver nitrate and cobalt nitrate staining, and the “deep-coned vertebrae” technique. The latter was discarded due to its unsuitability for tope shark vertebrae. The cobalt nitrate original protocol was modified. Upon staining, each vertebra was subject to three replicated independent readings, by a single reader. Within-reader consistency and bias of growth ring counts determination were evaluated using four different precision indices: percent of agreement (PA), average percent error (APE), coefficient of variation (V) and index of precision (D). Results indicated that
the vertebrae stained with the cobalt nitrate technique showed both better optic
enhancement of growth rings and higher degree of count consistency, comparatively to the alizarin red and silver stained vertebrae. Conclusively, the cobalt nitrate was the most efficient staining technique upon tope shark vertebrae, among the methods tested herein
Annotated list of fishes caught by the R/V ARQUIPÉLAGO off the Cape Verde archipelago.
A prospective survey was carried out in October - November of 2000, in the Cape Verde
archipelago, by the R/V ARQUIPÉLAGO. The main objective was to determine the
species composition and relative abundance of the demersal fish resources living in the
waters of the Cape Verde archipelago. A list of fishes caught with bottom longline during
the survey is presented in this document, along with information about the area, depth
limits and the relative abundance of the species in the catches. Ninety-seven different species from 49 families were identified from 20 long-line sets. To our knowledge, the following 12 species were recorded for the first time from the waters of Cape Verde islands: Etmopterus princeps, Etmopterus pusillus, Gymnothorax maderensis, Myroconger compressus, Laemonema robustum, Beryx splendens, Scorpaena elongata, Serranus
atricauda, Taractes rubescens, Taracthichthys longipinnis, Pagrus africanus and Cathidermis sufflamen. The species Laemonema robustum, were new to the CLOFETA
area
The Mauritanian Slope (NE Atlantic) Has No Desert: <em>Swiftia phaeton</em> (Holaxonia: Plexauridae) Shaping Coral Gardens
Swiftia Duchassaing & Michelotti, 1864, is often found sparse in the NE Atlantic Ocean and Mediterranean Sea. When the cruise MSM 16/3 “PHAETON” filmed the upper bathyal off Mauritania in 2010, the first dense populations dominated by Swiftia were discovered in the NE Atlantic Ocean, co-occurring with the framework-forming scleractinians Desmophyllum pertusum (Linnaeus, 1758) and Madrepora oculata Linnaeus, 1758. Remotely operated vehicle (ROV) video annotation from two canyons and two coral mounds considered Swiftia phaeton Sampaio, Beuck & Freiwald, 2022 presence, size class and abundance as well as substrate and geomorphology of the seafloor. Coral gardens definition included abundance and size of the species. Dense and very dense mono- and multispecific coral gardens dominated by S. phaeton were mapped between 20°24′N and 17°54′N in 470–640 m depth. The resilience of these coral gardens off Mauritania is mainly linked to the presence of hard substrate available to settle and to the exposition of currents rich in food. Still, these ecosystems are located inside a hydrocarbon exploration area off Mauritania and where fisheries occur since the 1960s. Sedimentation plumes caused by both activities can travel and impact on settlement, development, and survival of these populations. Hence, these vulnerable “oases” should be protected
Fishes of the Northern Mid-Atlantic Ridge collected during the MAR-ECO Cruise in June-July 2004. An annotated checklist.
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