Stock assessment of endemic tarek (Alburnus tarichi Güldenstädt, 1814) for the data-poor fishery from Lake Van (Türkiye)

Alburnus tarichi accounts for about 30% of the annual inland water catch in Turkey, which is about 33.000 tonnes. Lake Van is the world's largest alkaline lake and Turkey's largest lake at 3602 km2. Due to the unavailability of detailed data for the data-rich models, the stock of A. tarichi was assessed by the CMSY method based on catch data from 1967 to 2021. The values with their confidence intervals were computed for the Lake Van Tarek stock by the CMSY model are presented as follows: MSY=12.3 (10.8 - 14.2) ton*1000, k=92.4 (66.5 - 129) ton*1000, r=0.536 (0.377 - 0.76)*year-1, B2021=48.0 (29.4 - 55.1) ton*1000, BMSY=46.2 (33.2 - 64.3) ton*1000, F2021 = 0.202 (0.180 - 0.338)* year-1, FMSY = 0.268 (0.189 - 0.380)* year-1, F2021/FMSY = 0.772 (0.672 - 1.260), B2021/ BMSY = 1.04 (0.636 - 1.190). This study reveals that the stock of A. tarichi was subjected to significant and continuously increasing fishing pressure from the early unexploited years (1967 – 1996) and eventually became overfished in subsequent years (1997-2010). After the prohibition of summer fishing in 1997, which significantly reduced recruitment, the stock began to enter a recovery period in the early 2000s. As a result, the stock of A. tarichi has reached a sustainable level currently and has been assessed as a "healthy stock" based on the CMSY outputs.