Using cumulative human‐impact models to reveal global threat patterns for seahorses

Abstract

Understanding threats acting on marine organisms and their conservation status is vital but challenging given a paucity of data. We studied the cumulative human impact (CHI) on and conservation status of seahorses (Hippocampus spp.)—a genus of rare and data‐poor marine fishes. With expert knowledge and relevant spatial data sets, we built linear‐additive models to assess and map the CHI of 12 anthropogenic stressors on 42 seahorse species. We examined the utility of indices of estimated impact (impact of each stressor and CHI) in predicting conservation status for species with random forest (RF) models. The CHI values for threatened species were significantly higher than those for nonthreatened species (category based on International Union for Conservation of Nature Red List). We derived high‐accuracy RF models (87% and 96%) that predicted that 5 of the 17 data‐deficient species were threatened. Demersal fishing practices with high bycatch and pollution were the best predictors of threat category. Major threat epicenters were in China, Southeast Asia, and Europe. Our results and maps of CHI may help guide global seahorse conservation and indicate that modeling and mapping human impacts can reveal threat patterns and conservation status for data‐poor species. We found that for exploring threat patterns of focal species, species‐level CHI models are better than existing ecosystem‐level CHI models.

Monitoring of Seahorse Populations, in the Ria Formosa Lagoon (Portugal), Reveals Steep Fluctuations: Potential Causes and Future Mitigations

“…There is a big knowledge gap in mapping illegal fishing of seahorses as they are mostly unreported and are not regulated (Zhang and Vincent 2019). Illegal fisheries may be responsible for high pressures on seahorse population, particularly in the Ria Formosa lagoon (Correia et al 2015a;Zhang and Vincent 2019) and may be partially responsible for the population decline reported in this study and ultimately can lead to the local extirpation of seahorses.…”

“…The seahorse trade is often difficult to track, as it is often considered small-scale, both in terms of catches and economic value, which makes it difficult to have an accurate perception of the magnitude of the seahorse collection (Foster et al 2016). There is a big knowledge gap in mapping illegal fishing of seahorses as they are mostly unreported and are not regulated (Zhang and Vincent 2019). Illegal fisheries may be responsible for high pressures on seahorse population, particularly in the Ria Formosa lagoon (Correia et al 2015a;Zhang and Vincent 2019) and may be partially responsible for the population decline reported in this study and ultimately can lead to the local extirpation of seahorses.…”

Global extinction risk for seahorses, pipefishes and their near relatives (Syngnathiformes)

“…Other Data Deficient species are assessed as such because little was known about the level of mortality that fisheries cause across their range. Research is urgently needed to properly evaluate the conservation status of the Data Deficient species; work could also be done to predict the status of Data Deficient species in the absence of additional data (Bland et al, 2017; Kindsvater et al, 2018; Zhang & Vincent, 2019).…”

Getting old: an endangered seahorse (Hippocampus whitei) lives for up to 7 years in the wild

“…spp. are facing extinction within the wild (IUCN, 2021; Zhang & Vincent, 2019), collecting data on longevity in H . spp.…”