Climate change, biological invasions, and the shifting distribution of Mediterranean fishes: A large‐scale survey based on local ecological knowledge

Abstract

Climate change and biological invasions are rapidly reshuffling species distribution, restructuring the biological communities of many ecosystems worldwide. Tracking these transformations in the marine environment is crucial, but our understanding of climate change effects and invasive species dynamics is often hampered by the practical challenge of surveying large geographical areas. Here, we focus on the Mediterranean Sea, a hot spot for climate change and biological invasions to investigate recent spatiotemporal changes in fish abundances and distribution. To this end, we accessed the local ecological knowledge (LEK) of small‐scale and recreational fishers, reconstructing the dynamics of fish perceived as “new” or increasing in different fishing areas. Over 500 fishers across 95 locations and nine different countries were interviewed, and semiquantitative information on yearly changes in species abundance was collected. Overall, 75 species were mentioned by the respondents, mostly warm‐adapted species of both native and exotic origin. Respondents belonging to the same biogeographic sectors described coherent spatial and temporal patterns, and gradients along latitudinal and longitudinal axes were revealed. This information provides a more complete understanding of the shifting distribution of Mediterranean fishes and it also demonstrates that adequately structured LEK methodology might be applied successfully beyond the local scale, across national borders and jurisdictions. Acknowledging this potential through macroregional coordination could pave the way for future large‐scale aggregations of individual observations, increasing our potential for integrated monitoring and conservation planning at the regional or even global level. This might help local communities to better understand, manage, and adapt to the ongoing biotic transformations driven by climate change and biological invaders.

Marine recreational fishing and the implications of climate change

“…In many cases, recreational fishers have decades of knowledge of how fish species, size and seasonality have changed in their local area, and research which captures this local knowledge would be very valuable (e.g. Azzurro et al, ). Similarly, ongoing monitoring to capture future changes can help scientists understand climate effects and how to best manage them ().…”

“…Recreational anglers fishing in southern Europe may also see a substantial change in their catch as the surface air and sea temperatures are predicted to rise (Bethoux, Gentili, Raunet, & Tailliez, ; Giorgi & Lionello, ; Lejeusne, Chevaldonné, Pergent‐Martini, Boudouresque, & Perez, ). Recreational and small‐scale commercial fishers in the Mediterranean Sea have reported 75 species that have recently arrived or are increasing in abundance, and these are mostly warm‐adapted species, both native and non‐native (Azzurro et al, ). The expected rise in Mediterranean temperature may cause several commonly caught species, such as frigate tuna ( Auxis thazard, Scombridae), herring ( Clupea harengus, Clupeidae), sardines ( Sardina pilchardus, Clupeidae) and Atlantic horse mackerel ( Trachurus trachurus, Carangidae ; Khalfallah, Dimech, Ulman, Zeller, & Pauly, ; Matíc‐Skoko, Soldo, Stagličić, Blažević, & Iritani, ) to shift in distribution to the point where the catchability of these species by recreational anglers declines to zero.…”

Non-indigenous Species in the Mediterranean Sea: Turning From Pest to Source by Developing the 8Rs Model, a New Paradigm in Pollution Mitigation

“…The Mediterranean Sea is nowadays considered among the most impacted upon of the regional seas, due to the diverse anthropogenic pressures on the different ecosystems within the Mediterranean basin (Mannino et al, 2017). Among these, the most relevant are habitat loss and modification, climate change trends, eutrophication and pollution, coastal urbanization, overexploitation of natural resources, and intentional or unintentional introduction of NIS (Lejeusne et al, 2010;Zenetos et al, 2012;Katsanevakis et al, 2013;Marchini et al, 2015;Azzurro et al, 2019).…”

Fish and Sclerochronology Research in the Mediterranean: Challenges and Opportunities for Reconstructing Environmental Changes

“…In addition to the issues related to the availability of otolith collections, continuous sampling over several decades is also a challenge given the limited availability of funding for long-term studies and the logistics associated with field sampling. Longterm time series data are needed to estimate the real status of exploited resources and their evolution over time (Battaglia et al, 2010) and to analyze climate change effects on marine species and communities (Azzurro et al, 2019). Today, most scientific research projects are short in duration, resulting in difficulties related to securing funds needed for maintaining a longer data time series (Lleonart and Maynou, 2003;Rochet and Trenkel, 2003).…”