Shepherd, Scoresby. A. and Toral-Granda, Veronica and Edgar, G.J. (2003) Estimating the abundance of clustered and cryptic marine macro-invertebrates in the Galápagos with particular reference to sea cucumbers. Noticias de Galapagos, 62, pp. 36-39.
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Estimating the abundance of marine macro-invertebrates is complicated by a variety of factors: 1) human factors, such as diver efficiency and diver error; and 2) biological factors, such as aggregation of organisms, crypsis, and nocturnal emergence behavior. Diver efficiency varied according to the detectability of an organism causing under-estimation of density by up to 50% in some species. All common species were aggregated at scales from 10-50 m. Transects need to be long enough to transcend the scale of patchiness to improve accuracy. Some species of sea urchins and sea cucumbers (pepinos) which are cryptic by day emerged at night so that daytime censuses underestimated their abundance by up to 10 times. In the sea cucumber fishery, estimates of abundance need to be made at the scale of the population, i.e. at hundreds of km. A strategy for this is proposed.
|Title:||Estimating the abundance of clustered and cryptic marine macro-invertebrates in the Galápagos with particular reference to sea cucumbers|
|Journal or Publication Title:||Noticias de Galapagos|
|Page Range:||pp. 36-39|
|Issuing Agency:||Fundacion Charles Darwin Foundation|
|Uncontrolled Keywords:||sea cucumbers;Stichopus fuscus;Eucidaris;sea urchins;Lytechinus;sampling methods;surveys;diver efficiency;Isla Isabela;Isla Fernandina;Galápagos|
|Depositing User:||Ms Sally Taylor|
|Date Deposited:||16 Apr 2012 19:50|
|Last Modified:||16 Apr 2012 19:50|
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