Jake C. Rice

The dynamics of multispecies, multi-life-stage models of aquatic food webs

We investigated the dynamics of models of aquatic food webs using stability analysis methods previously applied to other types of food web models. Our models expanded traditional Lotka-Volterra models of predator-prey interactions in several ways. We added life history structure to these models in order to investigate its effects. Life history omnivory is different life history stages of a species feeding in trophically different positions in a food web. Such a species might appear omnivorous, integrating across all stages, but the individual stage might not be. Other important additions to the basic models included stock-recruitment relationships between adults and young and food-dependent maturation rates for early life history stages. Complex models of multispecies interactions were built from basic ones by adding new features sequentially. Our analysis revealed five major features of our multispecies, multi-life-stage models. Omnivory reduces stability, as it does in food web models without life history structure. However, life history omnivory reduces stability much less than single life stage omnivory does. Stock recruitment relationships affect the likelihood of finding stable models. If the maturation rate of young varies with their food supply, the chance of finding stable models decreases. Finally, predation loops of the type A eats B, B eats A, or A eats B, B eats C, C eats A greatly reduce model stability. We present both biological and mathematical explanations for these findings. We also discuss their implications for management of marine resources.

Challenges for Implementing an Ecosystem Approach to Fisheries Management

Abstract The ecosystem approach is being promoted as the foundation of solutions to the unsustainability of fisheries. However, because the ecosystem approach is broadly inclusive, the science for its implementation is often considered to be overly complex and difficult. When the science needed for an ecosystem approach to fisheries is perceived this way, science products cannot keep pace with fisheries critics, thus encouraging partisan political interference in fisheries management and proliferation of “faith-based solutions. In this paper we argue that one way to effectively counter politicization of fisheries decision-making is to ensure that new ecosystem-based approaches in fisheries are viewed only as an emergent property of innovation in science and policy. We organize our essay using three major themes to focus the discussion: empirical, jurisdictional, and societal challenges. We undertake at least partial answers to the following questions: (1) has conventional fisheries management really failed?; (2) can short-comings in conventional fisheries management be augmented with new tools, such as allocation of rights?; (3) is the Ecosystem Approach to Fisheries (EAF) equivalent to Ecosystem-Based Management?; and (4) is restoration of degraded ecosystems a necessary component of an EAF?

5 Dynamics of fish larvae, zooplankton, and hydrographical characteristics in the West Greenland large marine ecosystem 1950–1984

Abstract A relatively long series of plankton and hydrographic samples for the West Greenland ecosystem allows us to explore links between climate, physical oceanography, and abundance of major zooplankton and ichthyoplankton species. These linkages, manifest in food chains, fish stocks dynamics, and regime shifts in large marine ecosystems are important for fisheries management. Patterns of change in larval fish abundances and hydrographic characteristics were analyzed with data from three transects off southwest Greenland sampled between 1925 and 1984. Factor analysis and orthogonal varimax rotation on 8 physical oceanographic variables highlighted gradients in salinity, temperature, and temperature range (stratification). The period in the 1950s tended to be warmer than the 1970s, and a period of low salinity was present in the late 1960s and early 1970s. Non-parametric density estimation methods identified associations between the hydrographic characteristics and the distributions of fish and shrimp larvae: Atlantic cod ( Gadus morhua ), Redfish ( Sebastes marinus and S. mentella ), Greenland halibut ( Reinhardtius hippoglossoides ), Long rough dab ( Hippoglossoides platessoides ), Wolffish ( Anarhichas sp.), Sandeels ( Ammodytes sp.) and northern shrimp ( Pandalus borealis ). The fish larvae were generally distributed non-randomly to at least one of the hydrographic characteristics and to the indices of plankton and copepod abundance. The fish and shrimp larvae showed generally stronger associations with the indices of plankton and copepod abundance than with the hydrographic characteristics. The patterns suggest a suite of fish species whose larvae are weakly adapted to different oceanographic conditions and different ecological niches. For all but sandeels, June and July abundances are likely to be higher when water masses are relatively saline and well stratified, and when plankton, especially copepods, are abundant. These relationships were then carried further to determine synchronous temporal patterns among oceanographic characteristics, abundance indices of zooplankton, fish larvae, and year-class strengths. There was a decreasing trend in the plankton abundance indices from the late 1950s and early 1960s to the 1970s as well as a weak significant positive association to sea temperature. This trend culminated in the year 1969 and 1970 the period of the “Great Salinity Anomaly”. The variability in time series of zooplankton, fish and shrimp larvae could not be related to an impact of the GSA. There were weak significant associations between Atlantic cod year-class strength (given number at age 3) and both temperature and cod larvae abundance. The patterns explain reasonably well the decline in cod, redfish and long rough dab as consequences of changes in the relative influences of the East Greenland Polar Current and the Irminger Current, but do not explain the major increases in shrimp and Greenland halibut in the 1980s and 1990s. At least the former may be a consequence of reduced predation mortality. The associations are also generally consistent with a survey series of adult groundfish started in the 1980s in East and West Greenland waters.

Governance of marine fisheries and biodiversity conservation : interaction and coevolution

Governance of Marine Fisheries and Biodiversity Conservation explores governance of the world’s oceans with a focus on the impacts of two inter-connected but historically separate streams of governance: one for fisheries, the other for biodiversity conservation. Chapters, most co-authored by leading experts from both streams, investigate the interaction of these governance streams from ecological, economic, social and legal perspectives, with emphasis on policies, institutions processes, and outcomes on scales from the global to the local community, and with coverage of a range of themes and regions of the world.

Repeated cluster analysis of stomach contents data: method and application to diet of cod in NAFO division 3L

SynopsisData matrices of fish stomach contents frequently contain many zeros, and nonzero values often do not follow usually encountered statistical distributions. Therefore, many common methods of statistical analysis are inappropriate for such data. A method of repeated k-means cluster analysis is proposed for exploratory analysis of data sets on fish stomach contents. Objective rules are proposed for setting the clustering parameters, so the arbitrariness and subjectivity common in interpreting hierarchical clustering methods is avoided. Because the clusters are nonhierarchical, the analysis method also requires much less computer time and memory. Application of the method is illustrated with a data set of 1771 stomachs of cod (Gadus morhua), feeding on 38 different prey types. The results of the clusterings reveal that nine types of prey may account for the systematic information about the diet of cod in this sample from the northern Grand Bank in Spring of 1979. The results are also used to test specific hypotheses about size selectivity of the predator, spatial variation of feeding, environmental influences on diet, and relative preferences among prey taxa.

Kinetic studies on the rearrangement of 3,4-di-O-benzyl-1,2-O-(1-methoxyethylidene)-β-l-rhamnopyranose with a catalytic amount of 1,1,3,3-tetramethylurea-trifluoromethanesulfonic acid at different temperatures

Abstract The kinetics of the rearrangement of 3,4-di- O -benzyl-1,2- O -(1-methoxyethylidene)-β- l -rhamnopyranose to methyl 2- O -acetyl-3,4-di- O -benzyl-α- l -rhamnopyranoside with a catalytic amount of 1,1,3,3,-tetramethylurea-trifluoromethanesulfonic acid in deuterated chloroform was studied by 1 H-n.m.r. spectroscopy at different temperatures. This isomerization, irrespective of temperature, seems to occur by an intramolecular mechanism, and it follows first-order kinetics.

Arctic marine conservation is not prepared for the coming melt

Arctic marine conservation is not prepared for the coming melt Peter T. Harris*, Miles Macmillan-Lawler, Lars Kullerud, and Jake C. Rice GRID-Arendal, Postboks 183, N-4802 Arendal, Norway University of the Arctic, c/o GRID-Arendal, Postboks 183, N-4802 Arendal, Norway Department of Fisheries and Oceans, 200 Kent Street, Ottawa, ON K1A 0E6, Canada *Corresponding author: tel: þ47 47630434; e-mail: peter.harris@grida.no

Shaping the future of marine socio-ecological systems research: when early-career researchers meet the seniors

As the environmental issues facing our planet change, scientific efforts need to inform the sustainable management of marine resources by adopting a socio-ecological systems approach. Taking the symposium on Understanding marine socio-ecological systems: including the human dimension in Integrated Ecosystem Assessments (MSEAS) as an opportunity we organized a workshop to foster the dialogue between early and advanced-career researchers and explore the conceptual and methodological challenges marine socio-ecological systems research faces. The discussions focused on: a) interdisciplinary research teams versus interdisciplinary scientists; b) idealism versus pragmatism on dealing with data and conceptual gaps; c) publishing interdisciplinary research. Another major discussion point was the speed at which governance regimes and institutional structures are changing and the role of researchers in keeping up with it. Irrespective of generation, training or nationality, all participants agreed on the need for multi-method approaches that encompass different social, political, ecological and institutional settings, account for complexity and communicate uncertainties. A shift is needed in the questions the marine socio-ecological scientific community addresses, which could happen by drawing on lessons learnt and experiences gained. These require in turn a change in education and training, accompanied by a change in research and educational infrastructures.