A voluntary logbook scheme as a method of monitoring the by-catch of seals in Swedish coastal fisheries

Abstract Monitoring by-catches of marine mammals in fisheries is notoriously difficult. An alternative to observer programs or direct interviews with fishermen could be a detailed logbook system. In 1997 such a system was launched by the Swedish Fisheries Board, whereby fishermen were contracted to keep a detailed daily log of fish catches, seal disturbance (damage to gear and to fish and catch losses) and by-caught seals. In total, nearly 38,000 fishing records have been collected to date from a participating group of over 100 fishermen. The fishermen are compensated for their trouble with a small payment. To ensure that the information is properly recorded, all fishermen are contacted personally on a regular basis, and their entries are checked during site visits and by statistical means. In 2004, 22 grey seals, 4 ringed seals and 15 harbour seals were reported by-caught. The fishing effort represented by the participants in the logbook scheme is approximately 5 % of the total fishing effort in the Swedish coastal fisheries. These figures indicate that the total by-catch of seals in the Swedish fishing industry would be in the region of 900 animals annually. This figure tallies closely with the results from a telephone survey of 220 randomly selected fishermen in 2002. From that it was estimated that over 400 grey seals and harbour seals and 50 ringed seals were by-caught during the year 2001. By-catches as a relative proportion of the seal populations seem to be decreasing

Size selective capture of Atlantic cod (Gadus morhua) in floating pots

Little is known about the size selectivity of cod in static fishing gears such as pots and traps. In this field study, floating fishing pots were equipped with 40, 45 and 50 mm square mesh escape windows in order to estimate the size selectivity of cod at different mesh sizes. Relationships between selectivity parameters and mesh size, as well as an optimal mesh size for the escape window with respect to current minimum landing size of cod in the Baltic Sea were sought. The results show that the floating pot is not only species selective when used in the Baltic Sea cod fishery, the implementation of an escape window reduced the proportion of undersized bycatch in the pots by more than 90%. The estimated length at 50% retention was found to be a direct function of fish body length (girth) and mesh size of the escape window, while the estimated selection range remained unchanged regardless of mesh size. Optimal mesh size, with respect to the length at 50% retention and current minimal landing size of 38 cm in the Baltic, was determined to be 45 mm. Strong indications (significant on the 0.01 probability level in the case of 50 and 40 mm escape windows) suggested that the relative fishing power of the pots increased with the implementation of an escape window. This result could be explained as a "saturation effect", i.e. the probability of cod entering the pot is likely to be negatively dependent on cod density in the pot. The high species selectivity and the low catch rate of undersized fish have consolidated the floating pots position as a highly benign fishing method and the foremost alternative gear for the future coastal cod fishery in the Baltic Sea. (C) 2010 Elsevier B.V. All rights reserved

Anisakid nematodes and anisakiasis

Anisakiasis (anisakidosis) refers to infection of people with larval stages of ascaridoid nematodes belonging to the family Anisakidae (and possibly also Raphidascarididae). These worms, commonly called anisakids, utilize aquatic mammals, piscivorous birds, aquatic reptiles, or fish as definitive hosts, and aquatic invertebrates and fish as intermediate or paratenic hosts