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1.
J Fish Biol ; 103(2): 439-442, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37148473

RESUMEN

We report the first case of partial albinism in the Critically Endangered angelshark, Squatina squatina. The encounter with this specimen took place while SCUBA diving on the beach of Tufia, located on the east coast of the island of Gran Canaria on 2 April 2021. This is also the first confirmed finding of an albino elasmobranch specimen in the Canary Island archipelago.


Asunto(s)
Albinismo , Piebaldismo , Tiburones , Animales , España
2.
Mar Policy ; 133: 104712, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34608348

RESUMEN

Covid-19 pandemic has affected worldwide in many different ways. Fisheries around the world are not an exception due to the long-term isolation and the non-activities period suffered. To do an evaluation of its impact on the fishing sectors in the Canary Islands, 87 online and phone questionnaires were carried out between July and September 2020, conducting the interviews to artisanal fishermen, fishmongers, recreational charter boats fishermen and tackle shops along the archipelago. Both, the artisanal and recreational fishing sectors have been affected by this pandemic, but in an unequal manner. The drop of the demand of fresh fishing products in the islands markets due to the closure of hotels, restaurants and other services, and the highly significant decreasing in the number of tourists, provoked an estimated income loss for the artisanal fishermen about the 40% on average, but the majority of vessels continued their activities during the pandemic, with very limited effects on direct employment. However, the fishmonger's activity apparently was not affected and increased their monthly income in relation to the previous year. Likewise, the infeasibility of fishing charter companies due to the great reduction in the number of tourists contrasted with the significant increase in the number of recreational fishing licenses immediately after the confinement ended. Even though that fishing tackle shops increased sales by over 60% in relation to the similar period of the year before, only 4.4% of these shops declared not to have had economic losses.

3.
Animals (Basel) ; 13(9)2023 Apr 25.
Artículo en Inglés | MEDLINE | ID: mdl-37174492

RESUMEN

The presence of spiny butterfly rays, Gymnura altavela, in waters less than 20 m deep off the Canary Islands shows marked seasonality, with relatively high abundances in the summer and autumn. Large aggregations of sometimes hundreds of individuals, primarily females, appear in specific shallow areas of the archipelago and seem to be associated with the seasonal variation in water temperature. This seasonal pattern of presence or absence in shallow areas suggests that spiny butterfly rays migrate into deeper waters or other unknown areas during the rest of the year. G. altavela shows sexual dimorphism; in our study, females were larger and more abundant than males, with a sex ratio of 1:18.9. The species' estimated asymptotic length, L∞, was 183.75 cm and thus close to the common length reported for the species (200 cm). The von Bertalanffy growth constant (k) oscillated between 0.210 and 0.310 year-1, as similarly described for the species in the Western North Atlantic off the U.S. coast. From June to November, the seawater temperature oscillated between 19 and 24 °C, and massive aggregations of females occurred at 22-24 °C and in a few specific sandy beaches on the islands. Spiny butterfly rays, mostly females, show a preference for aggregating in shallow waters during summertime, probably conditionate to mating or breeding behaviour.

4.
Animals (Basel) ; 13(8)2023 Apr 21.
Artículo en Inglés | MEDLINE | ID: mdl-37106990

RESUMEN

Percnon gibbesi is a native crab species characteristic of intertidal and subtidal zones of the Atlantic coast of the European Macaronesian archipelagos (Azores, Madeira, and Canary Islands), and probably also in the neighbouring rocky coasts of northwest Africa. P. gibbesi is considered an invasive alien species in almost all of the Mediterranean, with expanding populations from Spain to Turkey, including Libya; However, its biology and ecology are highly unknown, despite all its range of distribution. In the intertidal zones of Gran Canaria Island, this crab, in the intertidal zones of Gran Canaria Island, shows a carapace length range between 4.1 and 22.7 mm (4.1-22.7 in males and 5.7-22.3 in females), where females showed higher weights and lengths than males on average; However, males predominated in all samples, with a sex ratio of 1:0.57. The L∞ for this crab was estimated to be 27 ± 3 mm (23 ± 4 mm for females and 25 ± 4 mm for males). The growth coefficient (K) was 0.24 year-1, the total mortality (Z) was Z = 1.71 year-1, and the natural mortality (M) was 0.47 year-1. Although females grow faster than males, males are more abundant in the larger length classes. Although the presence of ovigerous females indicated that reproduction takes place twice a year, from March to April and from August to September, the number of cohorts detected by the modal progression analysis showed that reproduction takes place all year.

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