Dr C Marshall
Dr C Marshall

Dr C Marshall

BSc (Guelph), MSc (McGill), PhD (Dalhousie)

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About

School of Biological Sciences Zoology Bldg., Z413 Tillydrone Ave. Aberdeen AB24 2TZ Scotland

External Memberships

Research

Research Overview

The overall aims of my research are to determine causes and consequences of variation in the life history of fish and to develop practical tools for implementing this knowledge into fisheries management.

The ocean is our research laboratory. We undertake collaborative research projects in a range of different ecosystems including:

  • sarcto-boreal ecosystems off the coast of Newfoundland and in the Barents Sea
  • shelf sea in the Southern Ocean surrounding South Georgia Island
  • coastal seas such as the North Sea and Norwegian Sea
  • estuarine conditions in the Northern Gulf of St Lawrence and the Baltic Sea.

We sample these ecosystems by participating in research vessel surveys and by accessing long-term databases generated from these surveys or from sampling of the commercial catch.

Much of our research focuses on two commercial species: cod and herring. Both have undergone well-documented collapses. Herring stocks in the North Sea and Norwegian Sea were overfished in the 1970s but were successfully rebuilt in the 1990s. Cod stocks in the Northwest Atlantic, North Sea and Baltic Sea are depleted or collapsed whereas the Barents Sea cod stock is currently above safe biological limits.

Current Research

Fish as key bioeconomic resources

Commercial fisheries are important socio-economic resources.  Because large-scale fisheries are often prosecuted by a number of different groups, management must operate by consensus if biological, economic and social sustainability is to be achieved. This requires effective means for attaining sustainable harvesting practices. Increasingly, my research is branching out into aspects of the bioeconomic performance of commercial fisheries. This includes investigating how short-term variability in fishers’ landings is generated because these fluctuations can influence economic returns from a fishery. Explaining short-term variability in landings could help to stabilise fisheries management and long-term landings. Another research theme has been examined is the impact of harvesting (or discarding) immature fish before they have spawned on sustainability. Future research will determine whether it is more economically and biologically sensible to allow fish to grow and reproduce in the future rather than harvest them now.

The ecological resiliency of populations to harvesting

The intrinsic rate of population growth (r) expresses the exponential rate of increase when abundance is low. Species having high r are regarded as inherently more resilient to harvesting compared to species having low r. Applying the same reasoning to a single harvested species, we would predict that r for stable or increasing populations should be sufficiently high to compensate for losses imposed by fishing whereas r for collapsed populations would be too low. To test this prediction we estimated cohort-specific r for two cod stocks, one currently within safe biological limits (Barents Sea cod) and the other collapsed since 1993 (Northern Gulf of St. Lawrence cod). Population increase in the healthy cod stock occurred when r was positive even after accounting for fishing. In the collapsed stock r was negative for several consecutive cohorts, effectively eliminating the stocks resiliency to fishing. Failure to recognize the magnitude of cohort-specific variation in r has led to misperceptions about the ability of depleted or collapsed populations to rebuild within desired time scales. We are now applying this analytical approach to model the collapse and recovery of Norwegian spring-spawning herring.

Climate-mediated changes in condition

Both reproduction and survival are affected by the "health" or condition of its individuals. Condition indices (CI) are used to represent the magnitude of stored energy reserves. Morphometric CI, analogous to Body Mass Index used for humans, are frequently used in roundfish species. We recently collaborated on research which suggests that a long-term trend towards decreased CI of salmon in two Scottish rivers is the result of increasing temperatures in the North Atlantic. Cod store lipids in their liver, consequently, the ratio of liver weight to body weight is a sensitive CI. Using a unique Russian database on liver weight of Barents Sea cod we have shown that temporal variability in the magnitude of stored energy is driven by fluctuations in both food and temperature. Herring are an oily fish storing a high proportion of lipids in their muscle tissue. Spatial variability in the fat content of North Sea herring has been investigated using a hand-held fat meter. Immature herring exhibit a south to north gradient in their fat content which could reflect a spatial gradient in availability of calanoid copepods. This research theme suggests that climate-mediated changes in availability of prey or temperature will have profound consequences for CI and therefore the population dynamics of many marine fish resources.

The ecophysiology of maturation

The rate at which individuals become sexually mature is a key determinant of the population growth rate, r. Many exploited fish stocks are maturing earlier. This could be a rapid evolutionary response to high selection pressure. Alternatively, changes in ecosystem functioning may also have contributed to energetic status of individuals so as to favour earlier maturation. Disentangling the genetic and environmental drivers that contribute to interannual variability in maturation rates is currently an active area of research. Herring are particularly plastic with respect to maturation rates which adds considerable uncertainty to management advice. The aim of our research is to describe the morphological, hormonal and gonadal changes which occur well in advance of maturation. Field sampling includes the measurement of fat content in muscles, steroid hormones in blood plasma, and structural changes in gonad tissue.

Tools for fisheries management

To achieve our aim of developing practical tools for implementing ecological knowledge into fisheries management we participate in a diverse range of collaborative projects:

  • model variation in growth rates of individuals so as to improve short-term forecasts (with FRS Marine Lab)
  • develop policy advice for rebuilding European fish stocks (with 17 partners)
  • evaluate the performance of alternative indices of stock reproductive potential in management strategy evaluations (with 12 member countries)
  • determine the likelihood of meeting international commitments to rebuilding stocks by 2015 (in collaboration with Cefas)

Several honours projects have been undertaken which use ICES databases to evaluate the long-term consequences of harvesting immature individuals.

Funding and Grants

June 2007: European Commission Cost Action FA0601awarded to consortium of 12 European countries for 4 years Fish Reproduction and Fisheries (ca €85,000 pa awarded to consortium to support training schools, workshops and symposia)

May 2007: BBSRC Quota PhD studentship Identifying hormonal and morphological markers associated with maturation in North Sea herring

Mar 2007: FRS Marine Laboratory ROAME Fisheries-induced evolution (£109,810)

Jan 2007: FRS Marine Laboratory ROAME An investigation into the visual assessment of maturity status in North Sea herring (£5,740)

Sep 2006: FRS Marine Laboratory Research Studentship Incorporating fish growth models in medium-term stock projections (£50,035)

Mar 2006: Royal Society Research Grants scheme Testing for developmental thresholds for maturation in North Sea herring (£10,910)

Feb 2006: The Nuffield Foundation Undergraduate research bursary Are visual assessments of maturity status for North Sea herring accurate? (£1,420)

Jan 2006: Royal Society of Edinburgh International Exchange Programme Visit of Dr. N.A. Yaragina (Polar Research Institute of Marine Fisheries and Oceanography, Murmansk) to University of Aberdeen (£1,810)

Jan 2006: FP6 European Commission UNCOVER – UNderstanding the mechanisms of stock reCOVERy (ca. £130,158)

May 2005: CASE partner Distell.com Do lipids impose a developmental threshold on the maturation of North Sea herring? (£4,500)

May 2005: BBSRC Quota CASE PhD studentship Do lipids impose a developmental threshold on the maturation of North Sea herring? (ca. £42,000)

Mar 2005: Royal Society of Edinburgh International Exchange Programme Trip to Polar Research Institute of Marine Fisheries and Oceanography, Murmansk (£1,464)

May 2004: BBSRC PhD studentship Time series analysis of cod bioenergetics with application to fish stock management (ca. £42,000)

Teaching

Teaching Responsibilities

  • Degree Programme Co-ordinator: Marine Biology degree
  • Course co-ordinator: ZO4538 Marine and Fisheries Biology, ZO5007 Fish Biology module in MSc programme
  • Course contributor: BI25Z2 Ocean Biology, BI29Z1 Fish and Shellfish Biology Field Course, ZO3508 Marine Ecology and Ecosystems, ZO3303 Animal Population Ecology

 

Publications

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  • The impact of electronic monitoring on fleet wide discarding of small cod in Scottish demersal fisheries

    Holah, H., Marshall, C. T., Needle, C., Fryer, R.
    ICES Journal of Marine Science, vol. 79, no. 6, fsac105
    Contributions to Journals: Articles
  • Intra- and inter-annual variability in the fat content of Atlantic herring (Clupea harengus) as revealed by routine industry monitoring

    Kenyon, S. E., Pastoors, M., Mackinson, S., Cornulier, T., Marshall, C. T.
    ICES Journal of Marine Science, vol. 79, no. 1, pp. 88-99
    Contributions to Journals: Articles
  • Estimating spatio-temporal distribution of fish and gear selectivity functions from pooled scientific survey and commercial fishing data

    Martin Gonzalez, G., Wiff, R., Marshall, C. T., Cornulier, T.
    Fisheries Research, vol. 243, 106054
    Contributions to Journals: Articles
  • How a new app helps fishing boats avoid endangered species

    Marshall, C. T.
    The Conversation
    Contributions to Specialist Publications: Articles
  • The environmental impacts of pelagic fish caught by Scottish vessels

    Sandison, F., Hillier, J., Hastings, A., Macdonald, P., Mouat, B., Marshall, C. T.
    Fisheries Research, vol. 236, 105850
    Contributions to Journals: Articles
  • Design, development and deployment of a software platform for real-time reporting in the west of Scotland demersal fleet: FIS032

    Marshall, C. T., Macdonald, P., Torgerson, E., Asare, J., Turner, R.
    Fisheries Innovation Scotland (FIS). 39 pages
    Books and Reports: Commissioned Reports
  • Can otolith microstructure and elemental fingerprints elucidate the early life history stages of the gadoid southern blue whiting (Micromesistius australis australis)?

    Busbridge, T. A., Marshall, C. T., Arkhipkin, A. I., Shcherbich, Z., Marriott, A. L., Brickle, P.
    Fisheries Research, vol. 228, 105572
    Contributions to Journals: Articles
  • Big Data in Marine Science

    Guidi, L., Fernandez Guerra, A., Canchaya, C., Curry, E., Foglini, F., Irisson, J. O., Malde, K., Marshall, C. T., Obst, M., Ribeiro, R. P., Tjiputra, J., Heymans, S. J. (ed.), Alexander, B. (ed.), Muñiz Piniella, ?. (ed.), Kellett, P. (ed.), Coopman, J. (ed.)
    Belgium: European Marine Board. 52 pages
    Books and Reports: Commissioned Reports
  • FIS workshop on Global synthesis of climate impacts on fish distribution and growth and implications for Scottish fisheries: FIS028

    Marshall, C. T., Baudron, A. R., Fallon, N. G., Spencer, P.
    Fisheries Innovation Scotland (FIS). 91 pages
    Books and Reports: Commissioned Reports
  • Accuracy of gonadosomatic index in maturity classification and estimation of maturity ogive

    Flores, A., Wiff, R., Ganias, K., Marshall, C. T.
    Fisheries Research, vol. 210, pp. 50-62
    Contributions to Journals: Articles
  • Is oxygen limitation in warming waters a valid mechanism to explain decreased body sizes in aquatic ectotherms?

    Audzijonyte, A., Barneche, D. R., Baudron, A. R., Belmaker, J., Clark, T. D., Marshall, C. T., Morrongiello, J. R., Itai, v. R.
    Global Ecology and Biogeography, vol. 28, no. 2, pp. 64-77
    Contributions to Journals: Articles
  • Feasibility study into a scientific self-sampling programme for the pelagic sector: FIS020

    Mackinson, S., Martin Gonzalez, G. F., Balestri, E., Coull, K., Clarke, E., Marshall, C. T.
    Fisheries Innovation Scotland (FIS). 111 pages
    Books and Reports: Commissioned Reports
  • Interannual variability in reproductive traits of the Patagonian toothfish Dissostichus eleginoides around the sub-Antarctic island of South Georgia

    Brigden, K. E., Marshall, C. T., Scott, B. E., Young, E. F., Brickle, P.
    Journal of Fish Biology, vol. 91, no. 1, pp. 278-301
    Contributions to Journals: Articles
  • Shifts in spawning phenology of cod linked to rising sea temperatures

    McQueen, K., Marshall, C. T.
    ICES Journal of Marine Science, vol. 74, no. 6, pp. 1561-1573
    Contributions to Journals: Articles
  • SMARTFISH: Selective management and retention of target fish FIS011B: FIS011 Developing and facilitating a range of possible future FIS projects in innovation in selectivity through on-net or alternative technologies

    Marshall, C., Wiff Onetto, R., Rosen, S., Neilson, R., Campos, R., Hwang, J., Fernandes, P.
    Fisheries Innovation Scotland (FIS). 67 pages
    Books and Reports: Commissioned Reports
  • Using commercial and survey data to infer real-time fish distribution in the North Sea at high resolution: Fishing Industry Science Alliance (FISA Project 01/15)

    Marshall, C., Wiff, R., Cornulier, T.
    Marine Scotland Science. 74 pages
    Books and Reports: Commissioned Reports
  • The unfulfilled potential of fisheries selectivity to promote sustainability

    Vasilakopoulos, P., O'Neill, F. G., Marshall, C. T.
    Fish and Fisheries, vol. 17, no. 2, pp. 399-416
    Contributions to Journals: Articles
  • Assessing consistency of fish survey data: uncertainties in the estimation of mackerel icefish (Champsocephalus gunnari) abundance at South Georgia

    Fallon, N. G., Collins, M. A., Marshall, C. T., Fernandes, P. G.
    Polar Biology, vol. 39, no. 4, pp. 593-603
    Contributions to Journals: Articles
  • Johan Hjort Symposium on Recruitment Dynamics and Stock Variability

    Kjesbu, O. S., Marshall, C. T., Nash, R. D. M., Sundby, S., Rothschild, B. J., Sinclair, M.
    Canadian Journal of Fisheries and Aquatic Sciences, vol. 73, no. 2, pp. VII-XI
    Contributions to Journals: Editorials
  • Real-time spatial management approaches to reduce bycatch and discards: Experiences from Europe and the United States

    Little, A. S., Needle, C. L., Hilborn, R., Holland, D. S., Marshall, C. T.
    Fish and Fisheries, vol. 16, no. 4, pp. 576-602
    Contributions to Journals: Articles
  • Resilience and tipping points of an exploited fish population over six decades

    Vasilakopoulos, P., Marshall, C. T.
    Global Change Biology, vol. 21, no. 5, pp. 1834-1847
    Contributions to Journals: Articles
  • Maturation shifts in a temperate marine fish population cannot be explained by simulated changes in temperature-dependent growth and maturity

    Wright, P. J., Palmer, S. C. F., Marshall, C. T.
    Marine Biology, vol. 161, no. 12, pp. 2781-2790
    Contributions to Journals: Articles
  • Bayesian fitting of probabilistic maturation reaction norms to population-level data

    McAdam, B. J., Marshall, C. T.
    Fisheries Research, vol. 159, pp. 105-113
    Contributions to Journals: Articles
  • The contribution of quota to the discards problem: A case study on the complexity of common megrim Lepidorhombus whiffiagonis discarding in the northern North Sea

    Macdonald, P., Cleasby, I. R., Angus, C. H., Marshall, C. T.
    ICES Journal of Marine Science, vol. 71, no. 5, pp. 1256-1265
    Contributions to Journals: Articles
  • Warming temperatures and smaller body sizes: synchronous changes in growth of North Sea fishes

    Baudron, A. R., Needle, C. L., Rijnsdorp, A. D., Marshall, C. T.
    Global Change Biology, vol. 20, no. 4, pp. 1023-1031
    Contributions to Journals: Editorials
  • Fishers' knowledge as an indicator of spatial and temporal trends in abundance of commercial fish species: Megrim (Lepidorhombus whiffiagonis) in the northern North Sea

    Macdonald, P., Angus, C. H., Cleasby, I. R., Marshall, C. T.
    Marine Policy, vol. 45, pp. 228-239
    Contributions to Journals: Articles
  • Report of the workshop on implementation of stock reproductive potential into assessment and management advice for harvested marine species

    Morgan, M. J., Marshall, C. T., O'Brien, L., Mosqueira, I., Cerviño, S.
    NAFO Scientific Council Studies, no. 44, pp. 1-75
    Contributions to Journals: Articles
  • Spatial variation in life history characteristics of common megrim (Lepidorhombus whiffiagonis) on the Northern Shelf

    Macdonald, P., Angus Née Laurenson, C. H., Marshall, C. T.
    Journal of Sea Research, vol. 75, pp. 62-68
    Contributions to Journals: Articles
  • Differential impacts of exploitation rate and juvenile exploitation on NE atlantic fish stock dynamics over the past half century

    Vasilakopoulos, P., O'Neill, F. G., Marshall, C. T.
    Fisheries Research, vol. 134-136, pp. 21-28
    Contributions to Journals: Articles
  • Misspent youth: does catching immature fish affect fisheries sustainability?

    Vasilakopoulos, P., O'Neill, F. G., Marshall, T.
    ICES Journal of Marine Science, vol. 68, no. 7, pp. 1525-1534
    Contributions to Journals: Articles
  • Implications of a warming North Sea for the growth of haddock Melanogrammus aeglefinus

    Baudron, A. R., Needle, C. L., Marshall, C. T.
    Journal of Fish Biology, vol. 78, no. 7, pp. 1874-1889
    Contributions to Journals: Articles
  • Inconsistencies in measurement of fish condition: a comparison of four indices of fat reserves for Atlantic herring (Clupea harengus)

    McPherson, L. R., Slotte, A., Kvamme, C., Meier, S., Marshall, C. T.
    ICES Journal of Marine Science, vol. 68, no. 1, pp. 52-60
    Contributions to Journals: Articles
  • Inaccuracies in routinely collected Atlantic herring (Clupea harengus) maturity data and correction using a gonadosomatic index model

    McPherson, L. R., Ganias, K., Marshall, T.
    Journal of the Marine Biological Association of the United Kingdom, vol. 91, no. 7, pp. 1477-1487
    Contributions to Journals: Articles
  • Lessons learned from stock collapse and recovery of North Sea herring: a review

    Dickey-Collas, M., Nash, R. D. M., Brunel, T., van Damme, C. J. G., Marshall, C. T., Payne, M. R., Corten, A., Geffen, A. J., Peck, M. A., Hatfield, E. M. C., Hintzen, N. T., Enberg, K., Kell, L. T., Simmonds, E. J.
    ICES Journal of Marine Science, vol. 67, no. 9, pp. 1875-1886
    Contributions to Journals: Articles
  • Are morphometric indices accurate indicators of stored energy in herring Clupea harengus?

    Davidson, D., Marshall, C. T.
    Journal of Fish Biology, vol. 76, no. 4, pp. 913-929
    Contributions to Journals: Articles
  • The evaluation of reference points and stock productivity in the context of alternative indices of stock reproductive potential

    Morgan, M. J., Murua, H., Kraus, G., Lambert, Y., Marteinsdottir, G., Marshall, T., O'Brien, L., Tomkiewicz, J.
    Canadian Journal of Fisheries and Aquatic Sciences, vol. 66, no. 3, pp. 404-414
    Contributions to Journals: Articles
  • The Importance of Reproductive Dynamics in Fish Stock Assessments

    Witthames, P. R., Marshall, C. T.
    Advances in Fisheries Science. Payne, A., Cotter, J., Potter, T. (eds.). BLACKWELL PUBLISHING LTD, pp. 306-324, 19 pages
    Chapters in Books, Reports and Conference Proceedings: Chapters
  • Factors contributing to inter- and intra-annual variation in condition of cod Gadus morhua in the Barents Sea

    Sandeman, L. R., Yaragina, N. A., Marshall, C. T.
    Journal of Animal Ecology, vol. 77, no. 4, pp. 725-734
    Contributions to Journals: Articles
  • Detrimental effects of recent ocean surface warming on growth condition of Atlantic salmon

    Todd, C. D., Hughes, S. L., Marshall, C. T., Maclean, J. C., Lonergan, M. E., Biuw, E. M.
    Global Change Biology, vol. 14, no. 5, pp. 958-970
    Contributions to Journals: Articles
  • The role of fisheries-induced evolution

    Browman, H. I., Law, R., Marshall, C. T.
    Science, vol. 320, no. 5872, pp. 47-50
    Contributions to Journals: Letters
  • The role of fisheries-induced evolution [1]

    Browman, H. I., Law, R., Marshall, C. T.
    Science, vol. 320, no. 5872
    Contributions to Journals: Letters
  • Integrated perspectives on genetic and environmental effects on maturation can reduce potential for errors of inference

    Marshall, C. T., McAdam, B. J.
    Marine Ecology Progress Series, vol. 335, pp. 301-310
    Contributions to Journals: Articles
  • Systematic bias in estimates of reproductive potential of an Atlantic cod (Gadus morhua) stock: Implications for stock-recruit theory and management

    Marshall, C. T., Needle, C. L., Thorsen, A., Kjesbu, O. S., Yaragina, N. A.
    Canadian Journal of Fisheries and Aquatic Sciences, vol. 63, no. 5, pp. 980-994
    Contributions to Journals: Articles
  • Comparison of various potential fecundity models for north-east Arctic cod Gadus morhua, L. using oocyte diameter as a standardizing factor

    Thorsen, A., Marshall, C. T., Kjesbu, O. S.
    Journal of Fish Biology, vol. 69, pp. 1709-1730
    Contributions to Journals: Articles
  • Systematic bias in estimates of reproductive potential of a cod (Gadus morhua) stock: implications for stock-recruit theory and management

    Marshall, C. T., Needle, C., Thorsen, A., Kjesbu, O. S., Yaragina, N. A.
    Canadian Journal of Fisheries and Aquatic Sciences, vol. 63, pp. 980-994
    Contributions to Journals: Articles
  • Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves

    Marshall, C. T., Needle, C., Yaragina, N., Ajiad, A. M., Gusev, E.
    Canadian Journal of Fisheries and Aquatic Sciences, vol. 61, no. 10, pp. 1900-1917
    Contributions to Journals: Articles
  • Developing alternative indices of reproductive potential for use in fisheries management: case studies for stocks spanning an information gradient

    Marshall, C. T., O'Brien, L., Tomkiewicz, J., Marteinsdottir, G., Morgan, M. J., Saborido-Rey, F., Koster, F., Blanchard, J. L., Secor, D. H., Kraus, G., Wright, P., Mukhina, N. V.
    Journal of Northwest Atlantic Fishery Science, vol. 33, pp. 161-190
    Contributions to Journals: Articles
  • Tracking the signal in year-class strength of Northeast Arctic cod through multiple survey estimates of egg, larval and juvenile abundance.

    Mukhina, N. V., Marshall, C. T., Yaragina, N. A.
    Journal of Sea Research, vol. 50, no. 1, pp. 57-75
    Contributions to Journals: Articles

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