Scottish lobster fisheries and environmental variability

Abstract

Variability in the fluctuations of two Scottish lobster populations, the Hebrides and Southeast, was investigated from available long dataseries of fishery and environmental variables. In a multivariate context, relationships between selected environmental variables and the fishery data were studied at different spatial and temporal (annual, spring, and autumn) scales and from individual and overall sampled fleet. Multivariate techniques such as cross-correlation function, principal components analysis, and redundancy analysis confirmed that the capture of lobsters was strongly influenced by sea surface temperature, windspeed, and sea level pressure throughout the year, and this dependence affected the duration of the fishery. There were evident differences in the patterns of environmental variables for both regions. In the Hebrides, the total variation (42%) of the interaction fishery-environmental variables for spring and autumn fisheries could be attributed to the environmental variables in an 89%. For the Southeast, spring fishery was more affected by changes in the environment, with a total variation of 34%, from which 85% could be explained by the environmental variables tested, than autumn fishery where catches and catch rates may be more affected by the way individual vessel and sampled fleet operate. Two elements were identified, Hebrides and Southeast spring and autumn fisheries. The Hebrides lobster population is strongly influenced by density-independence processes at all spatial scales. The Southeast fishery is also driven by environmental processes, with higher correlations for recruits with differences at small and large spatial scales.

Population Characteristics of the European Lobster, Homarus gammarus in the Adriatic Sea: Implications for Sustainable Fisheries Management

“…Our results also indicate extremely low catch rates, which could imply low abundance of this species in the study area, as was previously suggested by Pere et al [14]. However, fluctuations in H. gammarus abundance might occur as a consequence of a combination of environmental and fishery-related processes, like trap efficiency and target species behavior ( [26] and references therein), including feeding behavior and molting status [64]. It is long known that sea temperature affects behavior and availability of traps for homarid lobsters [65].…”

“…It is long known that sea temperature affects behavior and availability of traps for homarid lobsters [65]. In the present study, undersized specimens were predominantly caught in spring and autumn (>59%), likely due to the increase in lobster feeding activity prior and after spawning, and the increased sea temperature [26,28]. Sex ratio was slightly in favor of males, which might suggest a consistent female avoidance of traps year round, due to constant food or shelter-seeking behavior [66].…”

“…This species inhabits the whole Adriatic Sea, though population abundance is higher in the northern waters [23]. Studies on its biology and ecology in the Adriatic Sea as well as throughout the Mediterranean, are severely lacking in comparison with Northwestern European waters [22,[24][25][26][27][28][29]. Genetic analysis suggests a division between the stocks in the Atlantic and the Mediterranean Sea [30,31], and also between Mediterranean populations [32].…”

Enhancing fishery-dependent information in data-poor fisheries; integrating gear-in–gear-out sensors and mobile reporting technology in a mixed Irish Sea static-gear fishery

“…green crab Carcinus maenas-Murray and Seed 2010; king scallop Pecten maximus- Murray et al (2013); brown crab C. pagurus; and European lobster H. gammarus- Skerritt et al 2020), as well as underlying issues of data resolution, precision, and accuracy of reporting systems. These concerns relate to the effect of both environmental and biotic factors affecting overall catchability and interaction of the target species with the fishery/gear, such as inter-and intra-specific interactions (Skerritt et al, 2020), bait attraction (McQuinn et al, 1988), temperature (Lizárraga-Cubedo et al, 2015;Mullowney, 2016;Bakke et al, 2019), soak time (Bennett, 1974), and fisher targeting behaviours and associated local ecological knowledge (Santos et al, 2019). Factors that create variability in commercial LPUE are often overlooked because of over-simplistic approaches and static-environment assumptions, which are frequently built into traditional assessment and management tools (Szuwalski and Hollowed, 2016).…”

“…by-catch, discarding, population structure), or precise fishing activity locations among potentially highly heterogeneous fishing grounds. The inclusion of such variables are known to play a significant role on target species behaviour and subsequent interaction with fishing gear (Lizárraga-Cubedo et al, 2015) with consequent impacts on catchability and perceived abundance derived from fishery dependant data. Such variables are currently not routinely included in standardization of fishery-dependant data in part due to their lack of availability (Ernst and Addison, 2020).…”