Effects of exploitation on age, growth and mortality of the blackspot snapper, Lutjanus fulviflamma, at Mafia Island, Tanzania

  • Published source details Kamukuru A.T., Hecht T. & Mgaya Y.D. (2005) Effects of exploitation on age, growth and mortality of the blackspot snapper, Lutjanus fulviflamma, at Mafia Island, Tanzania. Fisheries Management and Ecology, 12, 45-55.


This study is summarised as evidence for the following.

Action Category

Restrict fishing activity (types unspecified) in a marine protected area

Action Link
Marine Fish Conservation
  1. Restrict fishing activity (types unspecified) in a marine protected area

    A site comparison study in 1999–2001 at four patch reef sites in the Indian Ocean, Tanzania (Kamukuru et al. 2005) found that inside a marine park with low fishing intensity, blackspot snapper Lutjanus fulviflamma were larger and older and had lower overall and fishing mortality rates, but no difference in growth rates than snapper in adjacent more intensively fished areas. Average size of snapper in low fishing areas was larger (211 mm) than the heavily fished areas (155 mm). The maximum snapper age was higher in low fishing intensity areas (low: 18 yrs, intensive: 8 yrs), and most individuals were 6–10 years old compared to mainly 2 and 4 year-olds in intensively fished areas. In the marine park, overall mortality (low: 0.55/yr, intensive: 1.64/yr) and fishing mortality (low: 0.18/yr, intensive: 1.37/yr) rates were lower compared to intensively fished areas. There were no significant differences in growth rates between all four sites (data given as growth parameters). Mafia Island Marine Park (822 km2) was established in 1995 as a multiple-use area and, although fishing was permitted in the park (details not reported), fishing intensity was significantly lower than in adjacent areas outside. Surveillance and enforcement were carried out within the park and action taken against illegal fishing. Data were collected from two sampling sites within the park with low fishing intensity (3.6–5.1 fishermen/km2) and two outside sites with high fishing intensity (6.4–8.6 fishermen/km2). From May 1999 to April 2001, monthly samples of snapper were collected from traditional vessels using seine nets. Snapper numbers, lengths and weights were recorded and the ear stones (otoliths) removed for determination of age and growth.

    (Summarised by: Ros McIntyre)

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