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

Abstract

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.

Life History and Fishing Aspects of the Deep-Sea Silver Scabbardfish Lepidopus caudatus in the Azores

“…This study provides new information on life history aspects and habitat preferences for L. caudatus . Like other demersal fishes from the Azorean region [ 48 , 49 ], as well in the Mediterranean [ 50 ] and the Atlantic [ 51 ], L. caudatus showed a spatial distribution mainly predicted by depth. Changes in depth generate variations in the physical and biological environment such as light intensity, temperature, salinity, predation and competition [ 50 , 52 , 53 ].…”

Metabarcoding fecal samples to investigate spatiotemporal variation in the diet of the endangered Westland Petrel ( Procellaria westlandica )

“…However, as stated before, it is also a known fishery species that could have been scavenged from the fishing waste. Besides, juveniles of several fish taxa, such as those from the Ophidiidae family, the common mora, Mora moro, (Santos et al 2021) or the king dory, Cyttus traversi, (Palomares and Pauly 2010) are known to be present in water surfaces and, therefore, they would be naturally available for the Westland Petrel if they fed on juveniles, as is the case of other Procellariiformes like the Leach's Storm Petrel (Oceanodroma leucorhoa; Watanuki 1985). It is as well worth remarking that Myctophid fishes, which were reported to be natural prey of the Westland Petrel (Imber 1976, Freeman 1998, were not identified in our sampling.…”

Biological Knowledge of Thornback Ray (Raja clavata) from the Azores: Improving Scientific Information for the Effectiveness of Species-Specific Management Measures

“…The presence of smaller individuals in shallower waters forming aggregations has been related to the use of coastal areas for growth before moving offshore [88,94]. Contrary to the survey that primarily samples the areas around the islands [24], fishing efforts have been directed to more offshore habitats [9,74,95], which could justify a slightly greater frequency in large individuals in commercial landings. This latter point, on the other hand, is also highly influenced by market prices and restriction measures such as minimum landing size (MLS).…”

“…In this regard, estimations of additional biological and fishery parameters, such as length at first maturity (L m ), length at maximum possible yield (L opt ), life span (t max ), and theoretical age at length zero (t 0 ), were performed by using the estimated growth parameters (L ∞ and k) as input of some empirical equations (Table S3) [118,119]. As well as other deep-water species [18,92,95,[120][121][122][123], R. clavata was characterized by the k-selected life history strategy with large size, slow growth, low natural mortality (Table 2), long life span, and late maturity (Table S1). The empirical equations also suggested a healthy fished population in the Azores, with the L c (Table S3) above the L m and L opt (Table S1), and the mean L T in the catch (Figure 5) above the L c , L m , and L opt .…”