Food composition and digestive enzymes in the gut of the African electric catfish Malapterurus electricus (Gmelin 1789) (Malapteruridae)

Analyses of stomach contents of 330 Malapterurus electricus (standard length, 10.1-30.5 cm) in Mahin Lagoon (southwestern Nigeria) established it as a bottom feeder. There was a preponderance of insects accounting for >80% occurrence and >25% of total volume in stomachs of specimens, suggesting a stenophagous predatory habit. Qualitative and quantitative assays of digestive enzymes in the different regions of the gut (oesophagus, stomach, duodenum, ileum, rectum) were investigated. Carbohydrases (amylase, maltase), chitinase, proteases (pepsin, chymotrypsin, trypsin) and lipases were detected in different gut regions with different activity. The pattern of distribution and relative activity of the enzymes correlated with the predatory diet

Aspects of the reproductive biology of Mugil cephalus (Linnaeus, 1857) in Bonny Estuary

Aspects of the reproductive biology of Mugil cephalus in the Bonny estuary (Nigeria) were studied between January and December 1996. Males were observed to be more slender than females while the females have deeper bodies. The male:female ratio (1:0:95) was not significantly different. The minimum size at maturity was 16.6cm (0.5 yr). Fish matured at 24.3cm TL(1.76 yr) with median maturity size of 19.5cm TL(0.71 yr). Median maturity for male and female fish were 16.4cm TL(0.41 yr) and 18.2cm TL(0.60 yr) respectively. Breeding occurred once a year between September and December, from late rainy season to early dry season. Mean absolute fecundity was 1,403, 808 eggs (range 107, 729-4,445, 423 eggs) for fish of 17.0.29.5cm TL (mean 22.5cm TL). Fecundity correlated positively with fish total weight, length, ovary weight and age

Colton Beck obstruction removal 1953

A worker drilling in Colton Beck,, North West England, UK, trying to make it more accessible for fish passing in 1953. This photo is part of a Photo Album that includes pictures from 1935 to 1954.

A report on the strategic stock assessment survey of the Colton Beck catchment 1994 with particular reference to salmonids

This is the report on the strategic stock assessment survey of the Colton Beck catchment in 1994 with particular reference to salmonids in Colton Beck, River Ea, River Gilpin and Rusland Pool. This report forms one part of the third year of a triennial survey programme for the South West Cumbria and South Cumbria catchments. It was produced by the National Rivers Authority in 1994. Colton Beck had excellent densities of sea trout (Salmo trutta) and a small population of salmon (Salmo salar) in its lowest reaches. The total productivity was very good throughout the catchment. Stocking of sea trout fry in 1993 has enhanced the population with survivors through to parr probably adding to the scoring of double class A at two sites in the survey in 1994. Stocking was not undertaken in 1994, but the population appears to be maintaining itself at a very high level.