Estimating total abundance of a large temperate-reef fish using visual strip-transects
Tóm tắt
Total abundance estimates for the large, common, reef fish Cheilodactylus spectabilis (Hutton) were obtained for a marine reserve and adjacent section of coast in north-eastern New Zealand during 1985. Visual strip-transects were used to estimate abundance and size structure in both areas. The accuracy, precision and cost efficiency of five transect sizes (500, 375, 250, 100, 75 m2) were examined over three times per day (dawn, midday and dusk), by simulating transects over mapped C. spectabilis populations. Two transect sizes showed similarly high efficiency. The smaller of the two (20x5 m) was chosen for the survey because of the general advantages attributable to small sampling units. Biases related to strip-transect size are discussed. Preliminary sampling indicated that C. spectabilis was distributed heterogeneously, and that density was habitat-related. An optimal stratified-random design was employed in both locations, to obtain total abundance and size-structure estimates. This reduced the between-habitat source of variability in density. The total number of sampling units used was governed by the time available. The resulting total abundance estimates obtained were 18 338±2 886 (95% confidence limit) for the 5 km marine reserve, compared to 3 987±1 117 for an adjacent, heavily fished 4 km section of coast. When corrected for total area and habitat area sampled, this represented a 2.3-fold difference in abundance. If sampling had been designed to detect an arbitrary 10% difference in abundance within each habitat, an infeasible 440 h of sampling would have been required. Size-frequency distributions of C. spectabilis at the reserve had a larger model size class than distributions from the adjacent area. The data suggest that reserve status is causal in these differing abundance and size structure estimates.
Tài liệu tham khảo
Andrew, N. L. and B. D. Mapstone: Sampling and the description of spatial pattern in marine ecology. Oceanogr. mar. Biol. A. Rev. 25 (1987). (In press)
Brock, R. E.: A critique of the visual census method for assessing coral reef fish populations. Bull. mar. Sci. 32, 269–276 (1982)
Caughley, G.: Bias in aerial survey. J. Wildl. Mgmt 38, 921–933 (1974)
Caughley, G.: Analysis of vertebrate populations, 234 pp. New York: John Wiley & Sons 1977
Choat, J. H. and A. M. Ayling: The relationship between habitat structure and fish faunas on New Zealand reefs. J. exp. mar. Biol. Ecol. 110, 257–284 (1987)
Choat, J. H. and D. R. Bellwood: Interactions amongst herbivorous fishes on a coral reef: influence of spatial variation. Mar. Biol. 89, 221–234 (1985)
Choat, J. H. and D. R. Schiel: Patterns of distribution and abundance of large brown algae and invertebrate herbivores in subtidal regions of northern New Zealand. J. exp. mar. Biol. Ecol. 60, 129–162 (1982)
Cochran, W. G.: Sampling techniques, 330 pp. New York: John Wiley & Sons 1953
Cochran, W. G.: Sampling techniques, 3rd ed., 330 pp. New York: John Wiley & Sons 1977
Downing, J. A. and M. R. Anderson: Estimating the standing biomass of aquatic macrophytes. Can. J. aquat. Sciences 42, 1860–1869 (1985)
Downing, J. A. and H. Cyr: Quantitative estimation of epiphytic invertebrate populations. Can. J. Fish. aquat. Sciences 42, 1570–1579 (1985)
Ebeling, A. W., R. J. Larson and W. S. Alevizon: Habitat groups and island-mainland distribution of kelp-bed fishes off Santa Barbara, California. In: Multidisciplinary Symposium on the California Islands, pp 403–431. Ed. by D. M. Power. Santa Barbara: Santa Barbara Museum of Natural History 1980
Emlen, J. T.: Population densities of birds derived from transect counts. Auk 88, 323–342 (1971)
Emlen, J. T.: Estimating breeding season bird densities from transect counts. Auk 94, 455–468 (1977)
Evans, C. D., W. A. Troyer and C. J. Lensink: Aerial census of moose by quadrat sampling units. J. Wildl. Mgmt 30, 767–776 (1966)
Fowler, A. J.: The development of sampling strategies for population studies of coral reef fishes. A case study. Coral Reefs 6, 49–58 (1987)
Francis, R. I.: Stratified random trawl surveys of deep-water demersal fish stocks around New Zealand. Occ. Publs Fish. Res. Div. N.Z. Minist. Agric. Fish. 32, 1–28 (1981)
Green, R. H.: Sampling design and statistical methods for environmental biologists, 257 pp. New York: John Wiley & Sons 1979
Grieg-Smith, P.: Quantitative plant ecology, 3rd ed., London: Blaekwell Scientific Publications 1983
Heisey, D. M. and J. M. Hoenig: Optimal allocation of effort in studies using the size frequency method of estimating secondary production. Limnol. Oceanogr. 31, 211–215 (1986)
Hixon, M. A.: Competitive interactions between California reef fishes of genus Embiotica. Ecology 6, 918–931 (1980)
Jones, G. P.: Population ecology of the temperate reef fish Pseudolabrus celidotus Bloch & Schneider (Pisces: Labridae). I. Factors influencing recruitment. J. exp. mar. Biol. Ecol. 75, 257–276 (1984a)
Jones, G. P.: Population ecology of the temperate reef fish Pseudolabrus celidotus Bloch & Schneider (Pisces: Labridae). II. Factors influencing adult density. J. exp. mar. Biol. Ecol. 75, 277–303 (1984b)
Jones, G. P.: The influence of habitat and behavioural interactions on the local distribution of the wrasse, Pseudolabrus celidotus. Envir. Biol. Fish. 10, 43–58 (1984c)
Kingett, P. D. and J. H. Choat: Analysis of density and distribution patterns in Chrysophrys auratus (Pisces: Sparidae) within a reef environment: an experimental approach. Mar. Ecol. Prog. Ser. 5, 293–290 (1981)
Leum, L. L. and J. H. Choat: Density and distribution patterns of the temperate marine fish Cheilodactylus spectabilis (Cheilodactylidae) in a reef environment. Mar. Biol. 57, 327–337 (1980)
Luckhurst, B. E. and K. Luckhurst: Analysis of the influence of substrate variables on coral reef fish communities. Mar. Biol. 49, 317–323 (1978)
McCormick, M. I.: Spatial and temporal patterns of abundance of Cheilodactylus spectabilis (Pisces: Cheilodactylidae), 113 pp. Unpublished MSc thesis, University of Auckland, New Zealand 1986
McDonald, L. L.: Summarizing remarks: observer variability. Stud. avian Biol. 6, 388–389 (1981)
Morin, A.: Variability of density estimates and optimization of sampling programs for stream benthos. Can. J. Fish. aquat. Sciences 42, 1530–1534 (1985)
Pringle, J. D.: Efficiency estimates for various quadrat sizes used in benthic sampling. Can. J. Fish. aquat. Sciences 41, 1485–1489 (1984)
Ralph, C. J. and J. M. Scott (Eds.): Estimating numbers of terrestrial birds. Stud. avian Biol. 6, 1–630 (1981)
Robinette, W. L., C. M. Loveless and D. A. Jones: Field tests of strip census methods. J. Wildl. Mgmt 38, 81–96 (1974)
Russ, G. R.: The distribution and abundance of herbivorous grazing fishes in the central Great Barrier Reef. I. Levels of variability across the entire continental shelf. Mar. Ecol. Prog. Ser. 20, 23–34 (1985)
Sale, P. F.: Ecology of fishes on the coral reefs. Oceanogr. mar. Biol. Rev. 18, 367–421 (1980)
Sale, P. F. and W. A. Douglas: Precision and accuracy of visual census technique for fish assemblages on coral patch reefs. Envir. Biol. Fish. 6, 333–339 (1981)
Sale, P. F. and B. J. Sharp: Correction for bias in visual transects of coral reef fishes. Coral Reefs 2, 37–42 (1983)
Sanderson, S. L. and A. C. Solonsky: A comparison of two visual survey techniques for fish populations (Abstract only). Pacif. Sci. 34, p. 337 (1980)
Sanderson, S. L. and A. C. Solonsky: Comparison of a rapid visual and a strip transect technique for censusing reef fish assemblages. Bull. mar. Sci. 39, 119–129 (1986)
Siniff, D. B. and R. O. Skoog: Aerial censusing of caribou using stratified random sampling. J. Wildl. Mgmt 28, 391–401 (1964)
Southwood, T. R.: Ecological methods, 391 pp. London: Chapman & Hall 1966
Thresher, R. E. and J. S. Gunn: Comparative analysis of visual census techniques for highly mobile reef associated piscivores (Carangidae). Envir. Biol. Fish. 17, 93–116 (1986)
Turner, L. J. and W. C. Mackay: Use of visual census for estimating population size in Northern pike (Esox lucius). Can J. aquat. Sciences 42, 1835–1840 (1985)
Wiebe, P. H.: A computer model study of zooplankton patchiness and its effects on sampling error. Limnol. Oceanogr. 16, 29–38 (1971)
Wiebe, P. H. and W. R. Holland: Plankton patchiness: effects on repeated net tows. Limnol. Oceanogr. 13, 315–321 (1968)