Skip to main content
SpringerLink
Log in

Assessing consistency of fish survey data: uncertainties in the estimation of mackerel icefish (Champsocephalus gunnari) abundance at South Georgia

  • Original Paper
  • Published:
Polar Biology Aims and scope Submit manuscript

Abstract

Mackerel icefish (Champsocephalus gunnari) is a semi-pelagic finfish species inhabiting shelf areas in the Southern Ocean. The population at South Georgia is currently exploited by pelagic trawlers fishing close to the seabed. Annual catches peaked at 150,000 t in 1983 and have declined since the mid-to-late 1980s. Bottom-trawl surveys have been conducted since 1987, providing a time series of abundance and size distribution for use in assessing the status of the stock and setting quotas. Food web models suggest that estimates of the biomass from survey data are substantially lower than the amount of icefish required by the local ecosystem. The aim of this study was to assess the uncertainty around current estimates of density and variance, using alternative nonparametric stratified bootstrapping methods. The stratified rescaling bootstrap estimator was identified as the most appropriate method of those tested: in comparison with the existing method, confidence intervals and the inter-annual variability of the estimates were reduced. Numbers-at-age were estimated from mixture distribution models fitted to length-disaggregated density data in order to determine whether individual cohorts were consistently detected by the surveys. Estimates of numbers-at-age could not consistently delineate cohorts in successive years indicating that survey-based estimates of density were biased. These biases may have arisen because the trawl gear did not select individuals of all sizes equally, or because sampling was restricted to the demersal component of the stock. Estimates of abundance of the pelagic component of the stock should be derived from acoustic data to improve the assessment.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

Similar content being viewed by others

References

  • Agnew D (1997) Review—the CCAMLR ecosystem monitoring programme. Antarct Sci 9:235–242

    Article  Google Scholar 

  • Agnew D, Everson I, Kirkwood G, Parkes G (1998) Towards the development of a management plan for the mackerel icefish (Champsocephalus gunnari) in Subarea 48.3. CCAMLR Sci 5:63–77

    Google Scholar 

  • Atkinson A, Siegel V, Pakhomov E, Rothery P (2004) Long-term decline in krill stock and increase in salps within the Southern Ocean. Nature 432:100–103

    Article  CAS  PubMed  Google Scholar 

  • Baudron AR, Fernandes PG (2014) Adverse consequences of stock recovery: European hake, a new “choke” species under a discard ban? Fish Fish. doi:10.1111/faf.12079

    Google Scholar 

  • Benaglia T, Chauveau D, Hunter DR, Young DS (2009) mixtools: an R package for analyzing finite mixture models. J Stat Softw 32:1–29

    Article  Google Scholar 

  • Caddy JF (2002) Limit reference points, traffic lights, and holistic approaches to fisheries management with minimal stock assessment input. Fish Res 56:133–137

    Article  Google Scholar 

  • CCAMLR (2012) Report of the working group on fish stock assessment. In: Report of the thirty-first meeting of the scientific committee (SC-CAMLR-XXXI), annex 7, Appendix G. Hobart, Australia

  • Chapman D, Robson D (1960) The analysis of a catch curve. Biometrics 16:354–368

    Article  Google Scholar 

  • Cochran WG (1977) Sampling techniques. Wiley, New York

    Google Scholar 

  • Cotter A, Mesnil B, Piet G (2007) Estimating stock parameters from trawl cpue-at-age series using year-class curves. ICES J Mar Sci 64:234–247

    Article  Google Scholar 

  • De la Mare WK (1994) Estimating confidence intervals for fish stock abundance estimates from trawl surveys. CCAMLR Sci 1:203–207

    Google Scholar 

  • De la Mare WK, Williams R (1996) Estimates of absolute recruitment for patagonian toothfish (Dissostichus eleginoides) around Heard Island. CCAMLR WG-FSA-96/38

  • Dickson W (1993) Estimation of the capture efficiency of trawl gear. I: development of a theoretical model. Fish Res 16:239–253

    Article  Google Scholar 

  • Efron B, Tibshirani RJ (1993) An introduction to the bootstrap, First. Chapman & Hall, New York

    Book  Google Scholar 

  • Everson I, Bravington M, Goss C (1996) A combined acoustic and trawl survey for efficiently estimating fish abundance. Fish Res 26:75–91

    Article  Google Scholar 

  • Everson I, Parkes G, Kock K-H, Boyd IL (1999) Variation in standing stock of the mackerel icefish Champsocephalus gunnari at South Georgia. J Appl Ecol 36:591–603

    Article  Google Scholar 

  • Frolkina Z (2002) Distribution of mackerel icefish (Champsocephalus gunnari) (Channichthyidae) around South Georgia at various stages of its life cycle. CCAMLR Sci 9:49–69

    Google Scholar 

  • Glass C, Wardle C (1989) Comparison of the reactions of fish to a trawl gear, at high and low light intensities. Fish Res 7:249–266

    Article  Google Scholar 

  • Hansen M, Madow W, Tepping B (1983) An evaluation of model-dependent and probability-sampling inferences in sample surveys. J Am Stat Assoc 78:776–793

    Article  Google Scholar 

  • Hill S, Reid K, North A (2005) Recruitment of mackerel icefish (Champsocephalus gunnari) at South Georgia indicated by predator diets and its relationship with sea surface temperature. Can J Fish Aquat Sci 2537:2530–2537

    Article  Google Scholar 

  • Hill SL, Murphy EJ, Reid K et al (2006) Modelling Southern Ocean ecosystems: krill, the food-web, and the impacts of harvesting. Biol Rev Camb Philos Soc 81:581–608

    Article  CAS  PubMed  Google Scholar 

  • Hill SL, Keeble K, Atkinson A, Murphy EJ (2012) A foodweb model to explore uncertainties in the South Georgia shelf pelagic ecosystem. Deep Sea Res Part II Top Stud Oceanogr 59–60:237–252

    Article  Google Scholar 

  • Hillary R, Edwards C, Mitchell R, Agnew DJ (2010) Length-based assessment for mackerel icefish (Champsocephalus gunnari) at South Georgia. CCAMLR Sci 17:129–137

    Google Scholar 

  • Kock K-H (2005) Antarctic icefishes (Channichthyidae): a unique family of fishes. A review, part I. Polar Biol 28:862–895

    Article  Google Scholar 

  • Kock K, Everson I (1997) Biology and ecology of mackerel icefish, Champsocephalus gunnari: an Antarctic fish lacking hemoglobin. Comp Biochem Physiol Part A Physiol 118:1067–1077

    Article  Google Scholar 

  • Macdonald P, Pitcher T (1979) Age-groups from size-frequency data: a versatile and efficient method of analyzing distribution mixtures. J Fish Board Can 36:987–1001

    Article  Google Scholar 

  • Main CE, Collins MA, Mitchell R, Belchier M (2008) Identifying patterns in the diet of mackerel icefish (Champsocephalus gunnari) at South Georgia using bootstrapped confidence intervals of a dietary index. Polar Biol 32:569–581

    Article  Google Scholar 

  • McConnaughey R, Conquest L (1993) Trawl survey estimation using a comparative approach based on lognormal theory. Fish Bull 91:107–118

    Google Scholar 

  • Mcquinn I, Simard Y, Stroud T et al (2005) An adaptive, integrated “acoustic-trawl” survey design for Atlantic cod (Gadus morhua) with estimation of the acoustic and trawl dead zones. ICES J Mar Sci 62:93–106

    Article  Google Scholar 

  • Mitchell RE, Belchier M, Gregory S, et al (2010) Results of the groundfish survey carried out in CCAMLR sub-area 48. 3 in January 2010. CCAMLR WG-FSA-10/38 38

  • Murphy EJ, Hofmann EE, Watkins JL et al (2013) Comparison of the structure and function of Southern Ocean regional ecosystems: the Antarctic Peninsula and South Georgia. J Mar Syst 109–110:22–42

    Article  Google Scholar 

  • North AW (2005) Mackerel icefish size and age differences and long-term change at South Georgia and Shag Rocks. J Fish Biol 67:1666–1685

    Article  Google Scholar 

  • Olsen MK, Schafer JL (2001) A two-part random-effects model for semicontinuous longitudinal data. J Am Stat Assoc 96:730–745

    Article  Google Scholar 

  • Parkes G (1991) The UK fish stock assessment survey bottom trawl for South Georgia. CCAMLR WG-FSA-91/16

  • Pennington M (1996) Estimating the mean and variance from highly skewed marine data. Fish Bull 94:498–505

    Google Scholar 

  • Reid K, Hill SL, Diniz TCD, Collins MA (2005) Mackerel icefish Champsocephalus gunnari in the diet of upper trophic level predators at South Georgia: implications for fisheries management. Mar Ecol Prog Ser 305:153–161

    Article  Google Scholar 

  • Särndal C, Thomsen I, Hoem J (1978) Design-based and model-based inference in survey sampling. Scand J Stat 5:27–52

    Google Scholar 

  • Saville A (1977) Survey methods of appraising fishery resources. Doc. Tech, FAO sur les Pech 171:68

  • Simmonds E, MacLennan D (2005) Fisheries acoustics. Theory and practice, 2nd edn. Blackwell Publishing Ltd, Oxford

    Book  Google Scholar 

  • Smith P (1993) Balancing sampling precision and fisheries management objectives: minimal methods. Bull Mar Sci 53:930–935

    Google Scholar 

  • Smith SJ (1997) Bootstrap confidence limits for groundfish trawl survey estimates of mean abundance. Can J Fish Aquat Sci 54:616–630

    Article  Google Scholar 

  • Stefánsson G (1996) Analysis of groundfish survey abundance data: combining the GLM and delta approaches. ICES J Mar Sci 53:577–588

    Article  Google Scholar 

  • Tarling G, Cuzin-Roudy J (2007) Recruitment of Antarctic krill Euphausia superba in the South Georgia region: adult fecundity and the fate of larvae. Mar Ecol Prog Ser 331:161–179

    Article  Google Scholar 

  • Thorson J, Stewart I (2011) Accounting for fish shoals in single-and multi-species survey data using mixture distribution models. Can J Fish Aquat Sci 68:1681–1693

    Article  Google Scholar 

  • Trathan P, Reid K (2009) Exploitation of the marine ecosystem in the sub-Antarctic: historical impacts and current consequences. Pap Proc R Soc Tasmania 143:9–14

    Google Scholar 

  • Trathan PN, Ratcliffe N, Masden EA (2012) Ecological drivers of change at South Georgia: the krill surplus, or climate variability. Ecography (Cop) 35:983–993

    Article  Google Scholar 

  • Von Szalay PG, Somerton DA, Kotwicki S (2007) Correlating trawl and acoustic data in the eastern Bering Sea: a first step toward improving biomass estimates of walleye pollock (Theragra chalcogramma) and Pacific cod (Gadus macrocephalus)? Fish Res 86:77–83

    Article  Google Scholar 

  • Waluda CM, Collins MA, Black AD et al (2009) Linking predator and prey behaviour: contrasts between Antarctic fur seals and macaroni penguins at South Georgia. Mar Biol 157:99–112

    Article  Google Scholar 

  • Wiedenmann J, Cresswell KA, Goldbogen J et al (2011) Exploring the effects of reductions in krill biomass in the Southern Ocean on blue whales using a state-dependent foraging model. Ecol Model 222:3366–3379

    Article  Google Scholar 

Download references

Acknowledgments

The authors wish to thank the crews, fishermen and scientists who conducted the various surveys from which data were obtained, and Mark Belchier and Simeon Hill for their contributions. This work was supported by the Government of South Georgia and South Sandwich Islands. Additional logistical support provided by The South Atlantic Environmental Research Institute, with thanks to Paul Brickle. Thanks to Stephen Smith of Fisheries and Oceans Canada (DFO) for help in constructing bootstrap confidence limits. Paul Fernandes receives funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland), and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. We also wish to thank two anonymous referees for their helpful suggestions on earlier versions of this manuscript.

Author information

Authors and Affiliations

  1. Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK

    Niall G. Fallon, C. Tara Marshall & Paul G. Fernandes

  2. Government of South Georgia and the South Sandwich Islands Government House, Stanley, Falkland Islands, FIQQ 1ZZ, UK

    Martin A. Collins

Authors
  1. Niall G. Fallon
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Martin A. Collins
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. C. Tara Marshall
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Paul G. Fernandes
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Niall G. Fallon.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Supplementary material 1 (DOCX 938 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Fallon, N.G., Collins, M.A., Marshall, C.T. et al. Assessing consistency of fish survey data: uncertainties in the estimation of mackerel icefish (Champsocephalus gunnari) abundance at South Georgia. Polar Biol 39, 593–603 (2016). https://doi.org/10.1007/s00300-015-1810-0

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00300-015-1810-0

Keywords

Search

Navigation