Aim: Whether marine species can respond to ocean warming by changing their depth remains controversial. Some evidence suggests that species can deepen to cope with warming climates, whereas other studies have found ecologically constrained depth distributions. Our study focuses on generalizing the depth response of species to warming and elucidating whether some species display a larger change in depth than others. This might help us to understand the future distribution of marine species and communities.

Stingrays and guitarfish are globally threatened by overexploitation, particularly so in the Mediterranean Sea. Nevertheless, very little information is known about their ecology, behaviour, and taxonomy in the Mediterranean, and especially in the Levant, where water temperature, salinity, and the impact of invasive species are relatively high. Although it has been suggested that some species may aggregate in the Levant, this has not been formally documented and the scale of this phenomenon, the taxonomic composition, and the temporal dynamics are unknown. Visual surveys were conducted, which allowed the documentation of stingrays and guitarfish behaviour, and which was not available from data based on fishery catches. The census took place within a marine protected area over a period of 3 years. Altogether, we documented 675 batoid observations. One of the observed species is Endangered (Glaucostegus cemiculus) and one is Vulnerable (Dasyatis pastinaca), whereas the others are classed as Least Concern (Torpedo torpedo and Torpedo marmorata), Data Deficient (Taeniurops grabatus), non‐assessed within the Mediterranean (Dasyatis chrysonota), and Not Evaluated (Himantura uarnak). Results show clear seasonal patterns, with dense aggregations recorded during spring and early summer, when densities reached 85 observations per kilometre. In addition, there were clear indications of breeding behaviour in D. pastinaca and D. chrysonota, including the first recorded documentation of D. pastinaca courtship in the Mediterranean. Large seasonal stingrays and guitarfish aggregations in shallow waters have not, to our knowledge, been documented in the Mediterranean Sea previously. This highlights the importance of conserving shallow habitats as potential breeding grounds. As these sites are easily reached while both snorkelling and diving, the aggregation of these charismatic species can serve as potential ecotourism sites. Finally, this study shows the benefits of using simple visual census, as opposed to catch‐based methods, to record both the diversity and the behaviour of batoids.

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For marine fishes, stressors such as ocean warming, biological invasions, and fisheries are suggested to drive depth redistributions. However, it is uncertain whether depth redistribution can act to offset the fitness costs associated with adverse changing conditions and allow species to maintain abundance. To better understand the relationship between global changes and depth redistribution, we synthesized bottom trawl surveys spanning two decades in the eastern Mediterranean Sea, a hotspot for warming and biological invasions, and ask three main questions: 1) have species changed their depth distributions?, 2) are patterns of depth change associated with changes in abundance? and 3) do depth and abundance changes differ by species traits and between indigenous and non‐indigenous species (NIS)? We found that patterns of depth change were highly variable. However, the relative abundances of species that exhibit deepening decreased while that of expanding species increased. Cold‐water species deepened more than warm‐water species and decreased in relative abundance. The majority of non‐indigenous fishes expanded their depth ranges over time and increased in relative abundance. The significant link between species' thermal preference and depth changes suggests that warming may drive depth redistributions. However, the variable depth change patterns imply that the hypothesis that species track climate change by deepening may be too simplistic. Finally, at least in the eastern Mediterranean, the deepening of indigenous species (IS) into colder waters was mostly associated with reduced abundance, hence deepening was not sufficient to offset the ecological impacts of global change.