Overfishing and habitat loss drive range contraction of iconic marine fishes to near extinction

Abstract

Extinctions on land are often inferred from sparse sightings over time, but this technique is ill-suited for wide-ranging species. We develop a space-for-time approach to track the spatial contraction and drivers of decline of sawfishes. These iconic and endangered shark-like rays were once found in warm, coastal waters of 90 nations and are now presumed extinct in more than half (n = 46). Using dynamic geography theory, we predict that sawfishes are gone from at least nine additional nations. Overfishing and habitat loss have reduced spatial occupancy, leading to local extinctions in 55 of the 90 nations, which equates to 58.7% of their historical distribution. Retention bans and habitat protections are urgently necessary to secure a future for sawfishes and similar species.

Tracking the rising extinction risk of sharks and rays in the Northeast Atlantic Ocean and Mediterranean Sea

“…Roughtail Stingray, Smalltooth Sand Tiger, and Great Hammerhead). Species’ sensitivity to both overfishing and climate change is higher at their range boundaries 41 , 42 , which may explain the greater deterioration of these species’ statuses (Fig. 1 b + c).…”

Environmental DNA metabarcoding reveals and unpacks a biodiversity conservation paradox in Mediterranean marine reserves

“…Marine ecosystems and their resources are severely threatened by multiple pressures including climate change [1], over-exploitation [2], and habitat degradation [3]. However, despite the prevailing trend of biodiversity loss at the global scale [4,5], the number of species does not necessarily decline at the local scale [6,7]. Long-term time series show that only 3% of coastal marine ecosystems are experiencing a local decline in species richness while a positive trend was reported in 16% of the studied cases [8].…”

Maximizing regional biodiversity requires a mosaic of protection levels

“…Species diversity is changing at all spatial scales under ever-increasing habitat degradation, spread of non-native species, overexploitation of resources, and climate warming [1][2][3][4]. Ambitious conservation targets have been recently proposed to halt and even reverse the ongoing biodiversity erosion with the commitment to protect at least 30% of the global ocean and land by 2030 [5,6].…”

“…Such arbitrary choices may have contributed to a marked species dissimilarity between adjacent Protected and Non-Protected areas primarily due to habitat differences within a region. Beyond this potential habitat effect, some conservation-dependent species can be extirpated by human activities outside protected areas [ 3 , 15 , 16 ] which may also increase species dissimilarity between protection levels. So, on the balance, the relative influence of local environmental conditions and protection level on species composition is still largely unknown, while the partial influence of protection level when controlling for environmental conditions, sample size, and species occurrences remains to be investigated across taxa and biomes.…”