Physiological aspects of the life cycle of the river lamprey, Lampetra fluviatilis L

The life cycle of the river lamprey, L. fluviatilis, is reviewed. The larval lamprey, or ammocoete, is a blind, filter-feeding animal, which normally lies concealed in the silt deposits of streams and rivers. After a period of 3-5 years in fresh water the ammocoete undergoes a metamorphosis in the summer months into a sexually immature, non-feeding stage known as the macrophthalia, which is active. This stage migrates downstream in late winter. It adopts a parasitic existence, in intertidal areas. After 18 months it returns to spawn in fresh water, after a final freshwater stage lasting up to 9 months. The river lamprey dies within a few days after the spawning period of 3-4 weeks, and none survive to spawn the following year.

Toward identification of larval sailfish (Istiophorus platypterus), white marlin (Tetrapturus albidus), and blue marlin (Makaira nigricans) in the western North Atlantic Ocean*

The identification of larval istiophorid billfishes from the western North Atlantic Ocean has long been problematic. In the present study, a molecular technique was used to positively identify 27 larval white marlin (Tetrapturus albidus), 96 larval blue marlin (Makaira nigricans), and 591 larval sailfish (Istiophorus platypterus) from the Straits of Florida and the Bahamas. Nine morphometric measurements were taken for a subset of larvae (species known), and lower jaw pigment patterns were recorded on a grid. Canonical variates analysis (CVA) was used to reveal the extent to which the combination of morphometric, pigment pattern, and month of capture information was diagnostic to species level. Linear regression revealed species-specific relationships between the ratio of snout length to eye orbit diameter and standard length (SL). Confidence limits about these relationships served as defining characters for sailfish >10 mm SL and for blue and white marlin >17 mm SL. Pigment pattern analysis indicated that 40% of the preflexion blue marlin examined possessed a characteristic lower jaw pigment pattern and that 62% of sailfish larvae were identifiable by lower jaw pigments alone. An identification key was constructed based on pigment patterns, month of capture, and relationships between SL and the ratio of snout length to eye orbit diameter. The key yielded identifications for 69.4% of 304 (blind sample) larvae used to test it; only one of these identifications was incorrect. Of the 93 larvae that could not be identified by the key, 71 (76.3%) were correctly identified with CVA. Although identif ication of certain larval specimens may always require molecular techniques, it is encouraging that the majority (92.4%) of istiophorid larvae examined were ultimately identifiable from external characteristics alone.

The role of small indigenous fish species in food and nutrition security in Bangladesh

In Bangladesh, only 6% of the daily food intake is animal food of which fish accounts for 50%. Rice is the mainstay, making up 60% of the daily food intake. However, many nutrients such as vitamins A and C, iron, calcium, zinc and iodine are not found in rice and have to be obtained from other sources. Small indigenous fish are a vital contribution to the diet of the rural poor in Bangladesh, where more than 30,000 children go blind every year from vitamin A deficiency and 70% of women and children are iron-deficient. Small fish, which are less than 10 cm in length and usually eaten whole with the organs and bones, contain large amount of calcium and possibly iron and zinc. The largest fish promoted in aquaculture do not contribute significantly to calcium intake. Some species also contain large amount of vitamin A. Much of the small indigenous fish (SIS) of Bangladesh are caught in floodplains and natural waterbodies. Small fish are eaten frequently in small amounts and are more equally distributed among family members than big fish of which men get the larger share. Unfortunately, overfishing and the deterioration of natural habitats have resulted in a decline in SIS. When measures are taken to improve food and nutrition security, there should be a focus on production of small fish so that greater quantities are accessible for consumption by the rural poor.