Aggregative Behaviour of Spiny Butterfly Rays (Gymnura altavela, Linnaeus, 1758) in the Shallow Coastal Zones of Gran Canaria in the Eastern Central Atlantic.

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.

First record of partial albinism in the critically endangered Angelshark (Squatina squatina) (Linnaeus, 1758).

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.

Life History Parameters and Fishing Aspects of the Alien Nimble Spray Crab Percnon gibbesi in a Native Area of the Central-East Atlantic.

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.

Differences in the occurrence and abundance of batoids across an oceanic archipelago using complementary data sources: Implications for conservation.

Batoids, distributed from shallow to abyssal depths, are considerably vulnerable to anthropogenic threats. Data deficiencies on the distribution patterns of batoids, however, challenge their effective management and conservation. In this study, we took advantage of the particular geological and geomorphological configuration of the Canary Islands, across an east-to-west gradient in the eastern Atlantic Ocean, to assess whether patterns in the occurrence and abundance of batoids varied between groups of islands (western, central, and eastern). Data were collected from shallow (<40 m, via underwater visual counts and by a local community science program) and deep waters (60-700 m, via ROV deployments). Eleven species of batoids, assessed by the IUCN Red List of Threatened Species, were registered, including three "Critically Endangered" (Aetomylaeus bovinus, Dipturus batis, and Myliobatis aquila), three "Endangered" (Gymnura altavela, Mobula mobular, and Rostroraja alba), two "Vulnerable" (Dasyatis pastinaca and Raja maderenseis), and two "Data Deficient" (Taeniurops grabata and Torpedo marmorata). Also, a "Least Concern" species (Bathytoshia lata) was observed. Overall, batoids were ~1 to 2 orders of magnitude more abundant in the central and eastern islands, relative to the western islands. This pattern was consistent among the three sources of data and for both shallow and deep waters. This study, therefore, shows differences in the abundance of batoids across an oceanic archipelago, likely related to varying insular shelf area, availability of habitats, and proximity to the nearby continental (African) mass. Large variation in population abundances among islands suggests that "whole" archipelago management strategies are unlikely to provide adequate conservation. Instead, management plans should be adjusted individually per island and complemented with focused research to fill data gaps on the spatial use and movements of these iconic species.

Preliminary assessment of the impact of Covid-19 Pandemic in the small-scale and recreational fisheries of the Canary Islands.

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.

Temporal and spatial predictions of effect of alternative fishing policies for the Gran Canaria marine ecosystem.

In this paper we consider what may happen to the marine ecosystem of Gran Canaria Island within the 2030 horizon, if fishing strategies different from those currently in place were implemented and we evaluate the effect of, for example, reduction of recreational-artisanal fishing, limitation of catches (e.g. total allowable catches, TAC), or spatial distribution of fishing sectors. From all scenarios tested, only those that significantly reduce the high effort of the recreational fishing would allow the recovery of the most exploited stocks in the marine ecosystem in the short and medium-term. Moreover, the best management strategy, in contribution to abundance, was obtained with a scenario that has a spatial partition of exploitation rights between artisanal and recreational fishermen and includes no-fishing zones (NTZ). This work is a first attempt to use spatial and temporal models to assess the effectiveness of alternative fishery policies in the Canary Islands.

Historical photographs of captures of recreational fishers indicate overexploitation of nearshore resources at an oceanic island.

In this study, we used a historical collection of photographs taken by recreational fishers from 1940 to 2014, at the island of Gran Canaria, to show both a significant decrease in the mean total length of Epinephelus marginatus and a concurrent change in the composition of captures. Before 1980, the mean total length of fish caught and photographed was c. 100 cm, while after 2009 this was typically < 40 cm. Before 1980, the predominant captured species was E. marginatus (an apex predator), but currently the majority of catches are of omnivorous species, in particular the parrotfish, Sparisoma cretense and seabreams Diplodus spp. Overall, integration of these results indicates a qualitative and quantitative variation in captures of recreational fishers, probably as a sign of change in ecological balances and the overfished status of many target species.