Historical photographs of captures of recreational fishers indicate overexploitation of nearshore resources at an oceanic island

Abstract

In this study, we used a historical collection of photographs taken by recreational fishers from 1940 to 2014, at the island of Gran Canaria, to show both a significant decrease in the mean total length of Epinephelus marginatus and a concurrent change in the composition of captures. Before 1980, the mean total length of fish caught and photographed was c. 100 cm, while after 2009 this was typically < 40 cm. Before 1980, the predominant captured species was E. marginatus (an apex predator), but currently the majority of catches are of omnivorous species, in particular the parrotfish, Sparisoma cretense and seabreams Diplodus spp. Overall, integration of these results indicates a qualitative and quantitative variation in captures of recreational fishers, probably as a sign of change in ecological balances and the overfished status of many target species.

iEcology: Harnessing Large Online Resources to Generate Ecological Insights

“…This showcases the potential of using voluminous search engine data to explore species distributions in many regions. Others have explored species occurrences and distributions using various sources, such as Flickr, news articles, Twitter, YouTube, Facebook, and Google Trends [13][14][15][16][17][18][19][20][21][22][23][24][25], as well as population dynamics and phenology [14,20,23,[26][27][28][29][30][31]. A particular illustration comes from assessing seasonal migration patterns of sockeye salmon (Oncorhynchus nerka) and Atlantic salmon (Salmo salar) from Wikipedia pageview frequencies (Figure 2B) [32].…”

“…Images of corals and tweets referring to corals have both been used to evaluate the state and trends of coral reefs in different areas, suffering from various human impacts [43,44]. Aspects of invasion dynamics [14,45] and overexploitation of fish [29,30] have also been studied using image analysis, tweets, and news articles. In the same way, behavioral changes in animals in response to anthropogenic impacts [46][47][48] can be tracked by such methods.…”

Expanding conservation culturomics and iEcology from terrestrial to aquatic realms

“…Culturomics and iEcology can help wildlife and fisheries managers monitor distributions, compositions, and dynamics of communities; fishing or hunting practices; fishers' or hunters' activities and behaviors; fisheries or managed harvest sustainability; and wildlife trade. 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 ].…”

Characterization and evolution of spearfishing in Madeira archipelago, Eastern Atlantic

“…However, spearfishing targets species inhabit rocky and reef habitats, which make them particularly vulnerable to exploitation (Jennings et al, 1999;Hawkins et al, 2000;Dulvy and Polunin, 2004;FAO, 2016;Meyer, 2007). Some target species can be slow growing, such as limpets (Sousa et al, 2017) or groupers (Jiménez-Alvarado et al, 2019), which exhibit low resilience under intense fishing pressure. Spearfishing can thus produce severe impacts on certain populations (Grau, 2008), affecting their abundance and reproductive potential (Garcia-Rubies and Zabala, 1990;Francour, 1991;Harmelin et al, 1995;Jouvenel and Pollard, 2001;Coll et al, 2004;Birkeland and Dayton, 2005;FAO, 2016;Rius, 2007).…”