Alien species stabilize local fisheries catch in a highly invaded ecosystem

Abstract

Alien species may be a valuable resource for marine fisheries, yet their contribution to the catch might be balanced by negative effects on indigenous species. In this study, we explored a unique high-resolution time series of catch data from a highly invaded ecosystem in the eastern Mediterranean. We analyzed over 5000 fishing hauls digitalizing from fishers’ logbooks. We found that the catch per unit effort (CPUE) of alien species increased over time, while for indigenous species, CPUE remained relatively stable between 1996 and 2013. This suggests a lack of competitive exclusion of indigenous target species due to the proliferation of alien species. From the perspective of the fishers’ revenues, alien species gradually became a more important part of the catch, while overall fishers’ revenues showed temporal stability. This was the combined result of alien species increasing CPUE and fishers shifting their effort toward shallower water where alien species were dominant. Our findings demonstrate that alien species can become a valuable resource for a local fishing industry with little effect on indigenous species, which is highly relevant to worldwide fisheries experiencing range redistribution of commercial species.

Advances in Egyptian Mediterranean Coast Climate Change Monitoring

“…Tropical fish generally grow faster [81], which can lead to a higher percentage of individuals reaching maturity [82], resulting in more numerous quantities than species of temperate origin. As reported by van Rijn et al [50], Lessepsian alien species are an advantage for fishermen for two main reasons. Firstly, because they show stability or increase the size of the population even when they are exploited.…”

“…For example, Nemipterus randalli, first identified in the Mediterranean in 2005 [69], is incorporated into local markets thanks to its great anatomical resemblance to native seabreds, although not part of the Sparidae. Alien species are considered a substitute for local ones, because they are preferred in terms of taste and even marketed at a higher price than local species [50]. Tropical fish generally grow faster [81], which can lead to a higher percentage of individuals reaching maturity [82], resulting in more numerous quantities than species of temperate origin.…”

“…Therefore, the fishermen must decide where to fish afterwards, often without prior knowledge of the distribution of the target species in the available fishing zone. In this uncertainty, even a shorter travel distance between possible locations is advantageous [50]. Periodic checks on diversity and on the community catalog can become a potential management tool for local administrations to protect and adapt the harbours for human and ecosystem health [84,85], and it can be done with alerts provided by local ecological knowledge (LEK), with morphological discrimination and/or molecular identification by barcoding using COI sequencing.…”

“…Monitoring of biological events related to climate change have given rise to an assessment of measures that may be taken towards enhancement of species adaptations and sustainability. Changes in biodiversity and the biological community due to climate change are not all negative and may sometimes be beneficial, with certain species either flourishing or successfully adjusting [48][49][50]. The majority of these observed changes are modest because of the relatively limited change in atmosphere that has occurred so far.…”

Expanding conservation culturomics and iEcology from terrestrial to aquatic realms

“…Several studies have inferred fish population trends and overfishing from temporal trends in fish size and composition using digitally stored data such as photographs and news articles [ 14 , 49 , 50 ]. Furthermore, historical data from digitized texts, photographs, or ship logs can provide insights into the distribution or abundance of species at times when scientific sampling data are limited [ 51 ]. Culturomics can shed light on the behavior and preferences of fishers [ 52 ], for example, by assessing regional characteristics of recreational fisheries based on YouTube videos or discussion forums ( Fig 1A ) [ 7 , 9 , 12 ] or by analyzing internet search frequency to explore global trends in fishing interest and seasonality [ 5 ].…”