Research on Determining of Mesh Size standard for Beach Seine Fishery cooperatives to Boost Sustainable Bony-Fish Fishery in Southern Caspian Sea.

Bony fish stocks are being legally utilized by 134 fishing cooperatives in the Iranian side of the Caspian Sea mainly through beach seine. This fishing method has been invariantly used over the past. Fifty years with actually no alteration or technical modifications in the fishing nets despite the substantial changes in the quality and quantity of bony fish resources. Based on the data obtained from the stock assessment project for bony fish, the amount of premature or young fish (substandard size) caught during the past decade has been far greater than those of authorized fish size and even the figures far certain species suggest heavy over fishing to such an extent that in the case of frisii kutum, there has been a reduction by 50% in the overall kutum landings.Thus in order to modify the technical design of the fishing with a view to alleviate the catch of non-standard fish and whereby prevent over fishing by beach seine, it seems imperative therefore to launch a biometric study on bony fish stocks particularly the two intended fish species namely Rutilus frisii kutum and mullet which would involve identification of their standard weight and length using pertinent mathematical equations as well as determining proper mesh size of the code-end and other parts of the nets and consequently the H. R, d/a coefficients. The operations related to project were carried out in the "Inland Aquaculture Research Institute"net mating plant and beach seine site in Anzali during 2005-7 which aimed at designing and constructing standardized beach seines and comparing the fishing performance and yields with those of ordinary beach seine nets under equal conditions with a ratio of 3:1. The results concerning the quality and quantity of fish caught during a whole fishing cycle were recorded in the related data forms. The statistical analysis consisting the comparison of the quality of fishing performance in both the experimental and control beach seine nets was made using T. student and excel, spss 12 software packages. The results indicated that the reduction in the amount of non-standard fish caught in standardized beach seine net (the experimental net) was meaningfully different from that of the ordinary (control) net showing the superior fishing performance of the former. The catch level of non-standard R.frisii kutum decreased from 67.1% in the control beach seine net down to 7.1% in the standardized beach seine net and these figures for mullet were 29.98% and 1.1% respectively. Based on the results obtained and considering the apparent superiority of the experimental net in catching greater number of mature fish and less number of premature or non-standard sized fish, the use of this modified beach seine net can be proposed to Iranian fisheries organization as a viable alternative to the traditional beach seine nets.