The once-abundant Mediterranean monk seal has been adversely impacted by human activities, ranging from exploitation for fur and oil to habitat fragmentation that have occured over many centuries. Today, one of the greatest threats facing the remaining seals is accidental entanglement in fishing nets. Bycatch mortality occurs throughout the species' range, and has been increasingly problematic since the 1980s (Guclusoy et al 2004). Bycatch data from the Ionian Sea spanning 25 years shows that the second leading cause of mortality (24% of total deaths) was accidental entanglement (Panou et al 1993). Juvenile seals are particularly at risk, as they are often not strong enough to free themselves from even the weakest of fishing nets. From 1991-2007, an estimated 46% of deaths in sub-adult Mediterranean monk seals in Greece were caused by accidental entanglement (Karamanlidis et al 2008). As net material becomes harder to escape from due to constantly improving fishing technology and more widespread use of nylon line, this aspect of the bycatch problem is amplified (Guclusoy et al 2004). Inherent to the problem is the fact that the seals will actively seek out fishing nets to raid for food. Depletion of fishing stocks in the region coupled with increased fishing effort not only results in less prey available for the seals, but also in increased incidents of entanglement (Johnson & Karamanlidis 2000). The consequences of net raiding are often dire, as fishermen are likely to deliberately kill the animals in order to reduce damage to gear and perceived competition for fish (Karamanlidis et al 2008). In a few places, marine protected areas have been established to safeguard Mediterranean monk seal colonies. For example, in Turkey's Foca Pilot Monk Seal Conservation Area, purse seining and trawling are prohibited (Guclusoy et al 2004). In Greece's National Marine Park of Alonnisos, Northern Sporades and in the Desertas Islands Nature Reserve in the Madeira Islands, comparable regulations as well as a ban on all unnecessary human activity near pupping sites exist (Karamanlidis et al 2008). Acoustic pingers have been utilized to try and warn seals away from nets with limited success (Karamanlidis et al 2008). Fishery closures, even on a limited scale, such as during the breeding season, appear to be a much more effective technique, and creation of marine protected areas near pupping sites also seems to decrease bycatch mortality (Mursaloglu 1984; Karamanlidis et al 2008). Despite these and numerous other conservation measures in place on paper, efforts have largely failed at reducing incidents of bycatch and protecting the species in general (Aguilar & Lowry 2008), and the threat of extinction for the species is high (van Blaricom et al 2001).
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