Northeast Atlantic

In the Northeast Atlantic, research vessel survey data reveal a decline in abundance indices by 38% since 1993 (Dureuil 2013), which is also suspected to have occurred over three generation spans (90 years). The relative exploitation rates are at levels that, on average, have been greater than that which is sustainable since 1997. In accordance, the fishing mortality from 1992 to 2012 for the central North Sea may have been two to four times greater than sustainable levels. Therefore, the spawning stock size of a cohort would have been reduced to approximately 15% of its exploited spawning stock biomass (Dureuil 2013). Within the English Channel there has been a decline in survey catch per unit effort (CPUE) of approximately 66.6% over the period 1988 to 2008 (Martin et al. 2010).

Tope landings throughout the Northeast Atlantic region have decreased by 83% in the past twenty years from a peak of 1,754 tonnes (t) in 1983 to the lowest record in the time series of 301 t in 2011 (ICES 2011). In the Baltic and North Sea region, landings steadily decreased between 1978 and 2011 (ICES 2012). Landings from waters off west Scotland, the Celtic Seas and the English Channel are relatively high, but also highly variable, with an overall decreasing trend since 1978 (ICES 2012).

Mediterranean

This species is now rare in the Mediterranean Sea, and while formerly common in the Adriatic Sea, it has not been captured there in the past half century. The analysis of the MEDITS program data from 1994-1999 shows a very low frequency of occurrence for this shark in the Mediterranean Sea (only five positive hauls or 0.05 %). Its overall biomass was estimated to be 0.2 kg/km² for the Mediterranean Sea. The standing stock biomass was estimated at 126 t (0.23%) (Baino et al. 2001). Off Italy, Relini et al. (2000) reported catch in only one of the 11 zones studied as part of the Italian national project (9,281 hauls in total, around the Italian coast, from 1985-1998), although data on biomass for this species were not provided. Tuna trap data from the Northern Tyrrhenian Sea from 1898 to 1992 shows a steep decrease in abundance of catches (80 individuals between 1898 and 1905; only eight for the 1906 to 1913 period and zero from 1914 to 1922) (Vacchi et al. 2002). Data from the MEDITS program for the Adriatic Sea were compared with those from the survey Hvar, carried out in 1948 (Jukic-Peladic 2001). Although no data on individual species captured biomass are reported, Tope appeared in the 1948 survey, but not in the MEDITS program. In Tunisian waters, where there exists a lower fishing pressure than off the northern Mediterranean coasts, the species is considered to be very rare (Bradai 2000).

Ferretti et al. (2013) noted that although offshore grounds of the Adriatic Sea remained almost unexploited until the end of World War II, the elasmobranch community surveyed was characterized by small, productive elasmobranchs. Larger, less resilient meso-predatory species such as Tope, which used to be common or seasonally abundant throughout the basin in the 19th and early 20th century (Marchesetti 1882, Ninni 1912, Paolucci 1901, Fortibuoni et al. 2010), were already scarce or under detectable levels (present in less than 5% of tows) likely due to decades of directed and incidental coastal fishing (Marchesetti 1882, Fortibuoni 2010). The Hvar and Zupanovic surveys operating in the Mediterranean Sea between 1948 and 1957 caught 18 Tope specimens in the Adriatic Sea, while the corresponding surveys since 1957 have never encountered the species again (Ferretti et al. 2013).

No species-specific catch data for the Mediterranean Sea and off northwest Africa were available in 2012 (ICES 2012). Overall, available landings appear relatively stable between 1982 and 2003 at around 500 t per year and at 400 t per year since 2004, with a drop to 300 t in 2011. However, the absence of some recent national data restricts the interpretation of recent trends. These older survey data suggest early depletion of Tope at least in shallow waters in this area, which could also have occurred in other Mediterranean areas where similar practices historically operated.

Considering that the stock of Tope is continuous throughout European waters, it is inferred that a similar decline to that of Northeast Atlantic waters is true for the Mediterranean Sea, therefore the species is inferred to have undergone a decline of 38% over the three-generation period through its European distribution.