Background

The year 2014 marked the 100th anniversary of contemporary science on fish population dynamics, after Johan Hjort proposed that fish populations are controlled through the survival success during the first few days of life (Hjort 1914). Growth and survival dynamics during the early life stages has been a focal point in studies on recruitment dynamics of fish for a long time. Larger and/or faster-growing individuals are more likely to survive than smaller and/or slower-growing conspecifics. This "growth–survival" paradigm originates from the "growth–mortality" hypothesis (Anderson 1988). Anderson (1988) concluded that this concept provides a rational theoretical framework for future studies. Indeed, the "growth–survival" paradigm has been given much attention in studies on recruitment dynamics of fish, with the leitmotiv of predicting recruitment dynamics. However, attempts of predicting recruitment from early growth dynamics has revealed difficult so far. Numerous field, laboratory, and modeling studies have tested the paradigm, contributing to early life biology and recruitment studies during the last quarter-century. In general, previous field studies tended to support the paradigm. On the contrary, some laboratory experiments provided evidence contrary to the paradigm. Moreover, recent studies revealed the variable nature of selective survival. Hence, the actual relationship between growth and survival appears to be much more variable and dynamic than previously recognized. More than 25 years after the publication of Anderson (1988), our objective is to review recent progress and expand the current paradigm in an attempt to reconcile contradictory results. Anderson, J. T. (1988) A review of size dependent survival during pre-recruit stages of fishes in relation to recruitment. Journal of Northwest Atlantic Fishery Science, 8: 55–66. Hjort J (1914) Fluctuations in the great fisheries of northern Europe viewed in the light of biological research. Rapports et Procès-Verbaux des Réunions du Conseil International pour l'Exploration de la Mer, 20: 1–228.

Objectives

An open-style symposium and a workshop (invited participants only) will be held to challenge fundamental issues on the "growth–survival" paradigm. The objectives of the present symposium/workshop are: (1) "Controversy": Extracting controversial issues on the paradigm. Contradictory results have been generated from field, laboratory, and modeling studies across systems and taxa. Moreover, results obtained from testing the paradigm tend to differ among study groups. We will extract controversial issues on the paradigm from previous studies by collecting a variety of perspectives. Key missing elements in previous and current studies will also be identified. (2) "Synthesis": Proposing ideas for reconciling and synthesizing contradictory results based on different perspectives from different study groups. A major goal of the present symposium is to figure out how to reconcile and synthesize contradictory evidence from field, laboratory, and modeling studies across systems and taxa. To achieve this goal, we will discuss the possibilities of producing literature reviews, comparative approaches, meta-analyses, and conceptual frameworks based on different perspectives from different study groups. (3) "Multidisciplinary approach": Promoting a collaborative framework for field, laboratory, and modeling studies. A collaborative framework for field, laboratory, and modeling studies will be needed to achieve the synthesis. In particular, this collaborative framework will incorporate results from field and laboratory studies into predictive models of recruitment dynamics. In addition to these major objectives, we will propose recommendations for future studies through discussion. The symposium is mainly constructed by oral presentations from invited speakers, although relevant contributed presentations may also be accepted. The goal of the subsequent workshop is to produce manuscripts for publication from the discussion of key topics. Overall, we aim to improve our understanding of growth–survival relationships in order to facilitate the prediction of recruitment dynamics through numerical modeling.

Our previous activities — What the organizers will propose as an introduction at the symposium

The present symposium/workshop was designed based on our previous activities through Japan–Canada collaboration workshops. At the symposium, we will propose a starting point for discussion. Here is a brief introduction of previous research activities.

Stage-I (Japan–Canada collaboration workshops)

To tackle the problem of the paradigm (see "Background"), we held Japan–Canada collaboration workshops on "Growth–survival paradigm in early life stages of fish: theory, advance, synthesis, and future" in October 2011 (Yokohama), May 2012 (Vancouver), and November 2013 (Yokohama). These workshops were designed to produce a review paper in which we expose our ideas and perspectives on the paradigm through synoptic reviews. Our review comprises 4 sections, as follows.

(1) "Theory": Summarizing a theoretical framework of the current "growth–survival" paradigm and its functional mechanisms.

(2) "Advance": Reviewing recent advances in studies on the paradigm.

(3) "Synthesis": Proposing a conceptual framework of growth–survival relationship which potentially reconciles contradictory evidence from field, laboratory, and modeling studies across systems and taxa.

(4) "Future": Presenting recommendations for future study directions.

A major result from the previous workshops (hereafter "Stage-I") was a conceptual framework of growth–survival relationship. The original paradigm has inherently assumed a linear growth–survival relationship, but we believe that this assumption is a possible reason for failures of prediction. We concluded that the growth–survival relationship can be nonlinear and vary with predator types. The conceptual framework was constructed based on the optimal foraging theory on the side of predators separately for three functional mechanisms for different predator types.

However, the ideas and perspectives in this review are not necessarily objective. Accordingly, we wish to collect a variety of ideas and perspectives broadly from different study groups for further progresses.

Stage-II (present symposium/workshop)

As the next step (hereafter "Stage-II"”), we aim to hold an international symposium/workshop by inviting experts from different countries to cover different ecosystems, taxonomies, approaches, etc. First, an open style symposium is held with presentations by invited speakers mainly. Different ideas and perspectives will be exchanged through this symposium. Then, a practical workshop is held by the organizers, invited speakers, and some collaborators in a closed style, to produce manuscripts for publication.

Proposals for Stage-II

The proposals for a starting point of discussion at the present symposium/workshop are:

(1) Extracting controversial issues on the review paper from Stage-I, in particular the proposed conceptual framework of growth–survival relationship (controversy).

(2) Synthesizing contradictory evidence with different perspectives from different study groups (synthesis).

(3) Revising the conceptual framework through the processes of (1) controversy and (2) synthesis.

(4) Incorporating the revised framework into predictive models of fish growth and survival for future simulation analyses under different conditions (multidisciplinary approach).

(5) Proposing update recommendations for future studies.

Stage-I workshops

Japan–Québec collaboration workshop on "Growth–survival paradigm in early life stages of fish: theory, advance, synthesis, and future" Yokohama, Japan, October 26 – November 1, 2011.

Japan–Québec collaboration workshop on "Growth–survival paradigm in early life stages of fish: theory, advance, synthesis, and future" Part II (follow-up workshop) Vancouver, Canada, May 23–26, 2012.

Japan–Canada collaboration workshop on "Growth–survival paradigm in early life stages of fish: theory, advance, synthesis, and future" Part III (follow-up workshop) Yokohama, Japan, November 8–15, 2013.

Presentations

Sirois, P., Takasuka, A., Robert, D., Shoji, J., Aoki, I., Fortier, L., Oozeki, Y. (2012) Size- or growth-selective mortality during early life history of fishes: publication bias and the need for a new conceptual framework. 36th Annual Larval Fish Conference, Bergen, Norway, July 2–6, 2012.

Sirois, P., Takasuka, A., Robert, D., Shoji, J., Aoki, I., Fortier, L., Oozeki, Y. (2012) Publication and citation biases in studies on growth and survival during early life stages of fish. Annual Meeting of Japanese Society of Fisheries Science, Tokyo, Japan, March 26–30, 2013.

Takasuka, A., Robert, D., Shoji, J., Sirois, P., Aoki, I., Fortier, L., Oozeki, Y. (2014) Growth–survival paradigm in early life stages of fish: theory, advance, synthesis, and future. 38th Annual Larval Fish Conference, Québec City, Canada, August 17–21, 2014 (Keynote Talk).

Takasuka, A., Robert, D., Shoji, J., Sirois, P., Aoki, I., Fortier, L., Oozeki, Y. (2014) Growth–survival paradigm in early life stages of fish: theory, advance, synthesis, and future. Annual Meeting of the Japanese Society of Fisheries Oceanography 2014, Yokohama, Japan, November 14–17, 2014.

Newsletters

Robert, D., Takasuka, A., Sirois, P., Shoji, J., Oozeki, Y. (2012) In Japan to review the growth–survival paradigm in fisheries oceanography. Québec-Océan Newsletter, 5 (February 2012): 3. [Newsletter]

Takasuka, A., Robert, D., Shoji, J., Sirois, P., Aoki, I., Fortier, L., Oozeki, Y. (2012) Workshops on growth–survival paradigm in early life stages of fish: the paradigm needs a synthesis. STAGES, 33 (2) (June 2012): 4–5. [STAGES]