Scientia Marina, Vol 70, No 3 (2006)

Use of commercial vessels in survey augmentation: the size-frequency distribution

Eric N. Powell
Haskin Shellfish Research Laboratory, Rutgers University,


The trend towards use of commercial vessels to enhance survey data requires assessment of the advantages and limitations of various options for their use. One application is to augment information on size-frequency distributions obtained in multispecies trawl surveys where stratum boundaries and sampling density are not optimal for all species. Analysis focused on ten recreationally and commercially important species: bluefish, butterfish, Loligo squid, weakfish, summer flounder, winter flounder, silver hake (whiting), black sea bass, striped bass, and scup (porgy). The commercial vessel took 59 tows in the sampled domain south of Long Island, New York and the survey vessel 18. Black sea bass, Loligo squid, and summer flounder demonstrated an onshore-offshore gradient such that smaller fish were caught disproportionately inshore and larger fish offshore. Butterfish, silver hake, and weakfish were characterized by a southwest-northeast gradient such that larger fish were caught disproportionately northeast of the southwestern-most sector. All sizes of scup, striped bass, and bluefish were caught predominately inshore. Winter flounder were caught predominately offshore. The commercial vessel was characterized by an increased frequency of large catches for most species. Consequently, patchiness was assayed to be higher by the commercial vessel in nearly all cases. The size-frequency distribution obtained by the survey vessel for six of the ten species, bluefish, butterfish, Loligo squid, summer flounder, weakfish, and silver hake, could not be obtained by chance from the size-frequency distribution obtained by the commercial vessel. The difference in sample density did not significantly influence the size-frequency distribution. Of the six species characterized by significant differences in size-frequency distribution between boats, all but one was patchy at the population level and all had one or more size classes so characterized. Although the variance-to-mean ratio was typically higher for the commercial vessel, five of the six cases that were otherwise were among the species for which the size-frequency distribution differed between the two vessels. Thus, the origin of the significant differences observed between vessels would appear to lie in the spatial pattern of the species as it interacts with the tendency for one vessel to obtain large catches more frequently for some size classes. One consequence of differential distribution and catchability is that more large fish were present in the commercial vessel catches than in the survey vessel catches in cases where the two vessels obtained different size-frequency distributions. Application of commercial vessels to the evaluation of size frequency hinges on understanding how to interpret differences among boats, gear, and sampling design. Here we show that key ingredients to this understanding are the degree of nonlinearity in catchability across a range of size classes, the interaction of varying spatial arrangements among size classes and the sampling design, and the interaction of varying spatial arrangements with differential catchability.


fish; survey; catchability; size-frequency distribution; spatial distribution

Full Text:



Brandt, S.B. and V.A. Wadley. – 1981. Thermal fronts as ecotones and zoogeographic barriers in marine and freshwater systems. Proc. Ecol. Soc. Australia, 11: 13-26.

Brodziak, J. and L. Hendrickson. – 1999. An analysis of environmental effects on survey catches of squids Loligo pealei and Illex illecebrosus in the northwest Atlantic. Fish. Bull., 97: 9-24.

Cadrin, S.X., A.B. Howe, S.J. Correia and T.P. Currier. – 1995. Evaluating the effects of two coastal mobile gear fishing closures on finfish abundance off Cape Cod. N. Am. J. Fish. Manag., 15: 300-315. doi:10.1577/1548-8675(1995)015<0300:ETEOTC>2.3.CO;2

Cliff, A.D. and J.K. Ord. – 1973. Spatial Autocorrelation. Pion Limited, London.

Conover, W.J. – 1980. Practical nonparametric statistics. John Wiley & Sons, New York.

Davis, J.C. – 1986. Statistics and data analysis in geology. John Wiley & Sons, New York.

Dawe, E.G. and L.C. Hendrickson. – 1998. A review of the biology, population dynamics, and exploitation of short-finned squid in the Northwest Atlantic Ocean, in relation to assessment and management of the resource. NAFO Doc., SCR 98/59.

Elliott, J.M. – 1977. Some methods for the statistical analysis of samples of benthic invertebrates. Freshw. Biol. Assoc. Sci. Publ., 25: 1-157.

El-Shaarawi, A.H. – 1985. Some goodness-of-fit methods for the Poisson plus added zeros distribution. Appl. Environ. Microbiol., 49, 1304-1306.

Fromentin, J-M., N.C. Stenseth, J. Gjøsaeter, O.N. Bjørnstad, W. Falck and T. Johannessen. – 1997. Spatial patterns of the temporal dynamics of three gadoid species along the Norwegian Skagerrak coast. Mar. Ecol. Prog. Ser., 155: 209-222. doi:10.3354/meps155209

Gabriel, K.R. and R.R. Sokal. – 1969. A new statistical approach to geographic variation analysis. Syst. Zool., 18: 259-278. doi:10.2307/2412323

Godø, O.R. – 1994. Factors affecting the reliability of groundfish abundance estimates from bottom trawl surveys. In: A. Ferno and S. Olsen (eds.), Marine fish behaviour in capture and abundance estimation, pp. 166-199. Blackwell Publishing, Cambridge, Massachusetts.

Gold, C.M., T.D. Charters and J. Ramsden. – 1977. Automated contour mapping using triangular element data structures and an interpolant over each irregular triangular domain. Computer Graphics, 11: 170-175. doi:10.1145/965141.563887

HSRL. – 2003a. Supplemental Finfish Survey Targeting Mid- Atlantic Migratory Species. March 2003 Cruise Report. Haskin Shellfish Research Laboratory, Rutgers University.

HSRL. – 2003b. Supplemental Finfish Survey Targeting Mid- Atlantic Migratory Species. May 2003 Cruise Report. Haskin Shellfish Research Laboratory, Rutgers University.

Jumars, P.A., D. Thistle and M.L. Jones. – 1977. Detecting twodimensional spatial structure in biological data. Oecologia (Berl.), 28: 109-123. doi:10.1007/BF00345246

Karp, W.A., C.S. Rose, J.R. Gauvin, S.K. Gaichas, M.W. Dorn and G.O. Stauffer. – 2001. Government-industry cooperative fisheries research in the North Pacific under the MSFCMA. Mar. Fish. Rev., 63(1): 40-46.

Lök, A., A. Tokaç, Z. Tosunoglu, C. Metin and R.S.T. Ferro. – 1997. The effects of different cod-end design on bottom trawl selectivity in Turkish fisheries of the Aegean Sea. Fish. Res., 32: 149-156. doi:10.1016/S0165-7836(97)00048-9

McCullagh, M.J. and C.G. Ross. – 1980. Delaunay triangulation of a random dataset for isarithmic mapping. Cartography J., 17: 93-99.

Morales-Bojórquez, E., S. Martínez-Aguilar, F. Arrequín-Sánchez, M.O. Nevárez-Martínez. – 2001. Estimates of catchability-atlength for the jumbo squid (Dosidicus gigas) fishery in the Gulf of California, Mexico. CalCOFI Rep., 42: 167-171.

NEFSC. – 1988. An evaluation of the bottom trawl survey program of the Northeast Fisheries Center. NOAA Tech. Mem., NMFSF/ NEC-52. 88 pp.

NEFSC. – 2000a. 30th northeast regional stock assessment workshop (30th SAW): Stock assessment review committee (SARC) consensus summary of assessments. NEFSC Ref. Doc., 00-03. 477 pp.

NEFSC. – 2000b. 31st northeast regional stock assessment workshop (31st SAW): Stock assessment review committee (SARC) consensus summary of assessments. NEFSC Ref. Doc., 00-15. 400 pp.

NEFSC. – 2001. Fishermen’s report bottom trawl survey Cape Hatteras-Gulf of Maine September 4-October 23, 2001. NMFS NEFSC.

NEFSC. – 2002. 34th Northeast Regional stock assessment workshop (34th SAW): Stock assessment review committee (SARC) consensus summary of assessments. NEFSC Ref. Doc., 02-06. 346 pp.

NEFSC. – 2003. 37th northeast regional stock assessment workshop (37th SAW): Stock assessment review committee (SARC) consensus summary of assessments. NEFSC Ref. Doc., 03-16, 603 pp.

Noreen, E.W. – 1989. Computer-intensive methods for testing hypotheses: an introduction. John Wiley & Sons, New York.

Otto, R.S. – 1986. Management and assessment of Eastern Bering Sea king crab stocks. Can. Spec. Publ. Fish. Aquat. Sci., 92: 83-106.

Pelletier, D. – 1998. Intercalibration of research survey vessels in fisheries: a review and an application. Can. J. Fish. Aquat. Sci., 55: 2672-2690. doi:10.1139/cjfas-55-12-2672

Perry, R.I. and S.J. Smith. – 1994. Identifying habitat associations of marine fishes using survey data: An application to the Northwest Atlantic. Can. J. Fish. Aquat. Sci., 51: 589-602. doi:10.1139/f94-061

Powell, E.N., A.J. Bonner, S.E. King and E.A. Bochenek. – (in press). Survey augmentation using commercial vessels in the Mid-Atlantic Bight: Sampling density and relative catchability. J. Appl. Ichthyol.

Powell, E.N., M.E. White, E.A. Wilson and S.M. Ray. – 1987a. Small-scale spatial distribution of a pyramidellid snail ectoparasitic, Boonea impressa, in relation to its host, Crassostrea virginica, on oyster reefs. P.S.Z.N.I.: Mar. Ecol., 8: 107-130. doi:10.1111/j.1439-0485.1987.tb00178.x

Powell, E.N., M.E. White, E.A. Wilson and S.M. Ray. – 1987b. Small-scale spatial distribution of oysters (Crassostrea virginica) on oyster reefs. Bull. Mar. Sci., 41: 835-855

Press, W.H., B.P. Flannery, S.A. Teukolsky and W.T. Vetterling. – 1989. Numerical recipes. Cambridge University Press, Cambridge.

Rago, P.J., K.A. Sosebee, J.K.T. Brodziak, S.A. Murawski and E.D. Anderson. – 1998. Implications of recent increases in catches on the dynamics of Northwest Atlantic spiny dogfish (Squalus acanthias). Fish. Res., 39: 165-181. doi:10.1016/S0165-7836(98)00181-7

Ricker, W.E. – 1975. Computation and interpretation of biological statistics of fish populations. Bull. Fish. Res. Board Canada, 191: 1-382.

Rogers, S.I., D. Maxwell, A.D. Rijnsdorp, U. Damm and W. Vanhee. – 1999. Fishing effects in northeast Atlantic shelf seas: Patterns of fishing effort, diversity and community structure. IV. Can comparisons of species diversity be used to assess human impacts on demersal fish faunas? Fish. Res., 40: 135-152. doi:10.1016/S0165-7836(98)00209-4

Schnute, J. – 1985. A general theory for analysis of catch and effort data. Can. J. Fish. Aquat. Sci., 42: 414-429.

Smith, S.J. and S. Gavaris. – 1993. Improving the precision of abundance estimates of eastern Scotian shelf Atlantic cod from bottom trawl surveys. N. Am. J. Fish. Manag., 13: 35-47. doi:10.1577/1548-8675(1993)013<0035:ITPOAE>2.3.CO;2

van der Meer, J. – 1997. Sampling design of monitoring programmes for marine benthos: A comparison between the use of fixed versus randomly selected stations. J. Sea Res., 37: 167-179. doi:10.1016/S1385-1101(97)00007-5

Walsh, S.J. – 1992. Size-dependent selection at the footrope of a groundfish survey trawl. N. Am. J. Fish. Manag., 12: 625-633. doi:10.1577/1548-8675(1992)012<0625:SDSATF>2.3.CO;2

Zheng, X., G.J. Pierce and D.G. Reid. – 2001. Spatial patterns of whiting abundance in Scottish waters and relationships with environmental variables. Fish. Res., 50: 259-270. doi:10.1016/S0165-7836(00)00219-8

Copyright (c) 2006 Consejo Superior de Investigaciones Científicas (CSIC)

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Contact us

Technical support