ISSN 1198-6727 Fisheries Centre Research Reports 2017 Volume 25 Number 1 Belated Contributions on the Biology of Fish, Fisheries and Features of Their Ecosystems Institute for the Oceans and Fisheries, The University of British Columbia, Canada Please cite as: Pauly D., Hood L., and Stergiou K.I. (eds.) Belated contributions on the biology of fish, fisheries and features of their ecosystems. Fisheries Centre Research Reports 25(1). 99pp. © Institute for the Oceans and Fisheries, The University of British Columbia, 2016 Fisheries Centre Research Reports are Open Access publications ISSN 1198-6727 Institute for the Oceans and Fisheries The University of British Columbia 2202 Main Mall Vancouver, B.C., Canada V6T 1Z4 2017 Fisheries Centre Research Reports 25(1) Fisheries Centre Research Reports 25(1) 2017 Edited by Daniel Pauly, Lincoln Hood and Konstantinos I. Stergiou CONTENT Preface ................................................................................................................................................. 3 Mediterranean slimehead, Hoplostethus mediterraneus in the Ionian Sea, Greece: Otolith Morphometry, Age and Growth ..................................................................................... 4 Aikaterini Anastasopoulou, Vasiliki Vassilopoulou, Stelios Katsanevakis and Paraskevi K. Karachle Interactions Between Growth, Sex, Reproduction, and Activity Levels in Control and Fast-Growing Strains of Nile Tilapia, Oreochromis niloticus ............................................ 15 Chantelle C. Bozynski and Daniel Pauly Indices for the Comparative Study of Fish Growth, with Emphasis on Red Bandfish Cepola macrophthalma ................................................................................................................3 4 Konstantinos I. Stergiou and Yong Chen Diet and Food Intake of Juvenile White-Spotted Spinefoot, Siganus fuscescens (Siganidae) .......................................................................................................................................4 0 Joselita T. Salita and Daniel Pauly The World Distribution of Capelin (Mallotus villosus): Views and Review .................. 49 Konstantinos I. Stergiou Tentative von Bertalanffy Growth Parameters of Little-Studied Fishes ......................... 58 Lincoln Hood and Daniel Pauly Aspects on Age and Growth of Helicolenus dactylopterus from the Deep Waters of the Eastern Ionian Sea .................................................................................................................. 61 Aikaterini Anastasopoulou, Chryssi Mytilineou, Gerasimos Dimitriadis and Christopher J. Smith. The Growth and Mortality of Sinarapan (Misticththys luzonensis) in Lake Manapao, Buhi, Camarines Sur Province, Philippines ......................................................... 67 Victor S. Soliman and Daniel Pauly Qualitative Observations on Plectropomus leopardus Behavior: Testable Expressions of the Oxygen-limitation Theory?............................................................................................... 71 Dirk Zeller Trends in Northeastern Mediterranean Artisanal Fisheries .............................................. 75 Konstantinos I. Stergiou, Athanasios Machias, Stylianos Somarakis and Argyris Kapantagakis Size Selectivity of Diamond and Square Mesh Cod-Ends in Four Mediterranean Fish Species ............................................................................................................................................... 85 Konstantinos I. Stergiou and George Petrakis Primary Production Enhancement by Oceanic Seamounts .............................................. 91 Daniel Pauly The Population Density of Monsters in Okanagan Lake, British Columbia ................. 95 Aran Kay and Daniel Pauly 2 PREFACE This report, as indicated in its title, contains mainly contributions initially written several years or even decades ago, but not formally published. They are now, because they contained ideas and/or data that may still be valuable. Two of the contributions in this volume are based on work conducted in the 1980s, a period during which manuscripts that remained unpublished could legitimately be cited, as exemplified by the unpublished essay on the effects of closing the Bering Strait on global climate, by the late Maxwell J. Dunbar. Currently, rules may be stricter, and it is thus appropriate to nudge unpublished essays from where they are, at the cusp of the transition from private knowledge to public knowledge. This accounts for the fact that, for scientists, it is act of publishing that counts; this is what connects them with other scientists, and opens the public debates that characterize science (besides establishing priority for any original idea). Nowadays, the journals’ guides to would-be-authors of scientific papers tend to stress that unpublished manuscripts (as opposed to material from the Internet, ephemeral or not) should not be listed in the ‘literature cited’ sections of papers. This can lead to the loss of valuable knowledge, and hence this compilation, through which we attempt to ‘save’, i.e., make more widely available what we could of some of the research that we, our graduate students and/or close colleagues have been conducting. The majority of the contributions deal with various aspects of the growth of fish, a major structuring feature of their life histories, and the basis of their productivity when under exploitation. When editing these contributions, we linked them, where appropriate, with the theory elaborated by one of us (D.P.), on the limiting role of fish gills, and hence oxygen supply, for the growth of fish, which has begun to attract attention, given observed and/or anticipated effects of global warming on fish growth. This theory explains, among other things: • Why fish (and aquatic invertebrates, as well) grow the way they do (asymptotically, predictably, temperature-dependent, etc.); • Why fish reach maturity at a size that is a predictable fraction of their maximum size even when the latter varies due to environmental forcing, but sometimes 'skip' spawning; • Why the food conversion efficiency of fish and aquatic invertebrates varies with size, temperature and dissolved oxygen; • Why fish larvae have very discernable daily rings on their otoliths (and squid larvae on their statoliths), which are less visible in adults; • Why visceral fat is abundant in cold temperate fish exhibiting strong seasonal growth oscillations, but not in tropical and polar fish exposed to narrow ranges of temperature; and • Why fish and aquatic invertebrates are spatially distributed the way they are, and why they migrate as they do. The other contributions in this report cover various topics in fisheries biology, marine ecology and ecosystem modelling, the last of which perhaps not being what it seems. Daniel Pauly Lincoln Hood Konstantinos I. Stergiou 3 2017 Fisheries Centre Research Reports 25(1) MEDITERRANEAN SLIMEHEAD, HOPLOSTETHUS MEDITERRANEUS IN THE IONIAN SEA, GREECE: OTOLITH MORPHOMETRY, AGE AND GROWTH* Aikaterini Anastasopoulou1, Vasiliki Vassilopoulou1, Stelios Katsanevakis2 and Paraskevi K. Karachle1 1 Institute of Marine and Biological Resources and Inland Waters, Hellenic Centre for Marine Research, Aghios Kosmas, Athens, Greece 2Department of Marine Sciences, University of the Aegean, University Hill, 81100 Mytilene, Greece [email protected] ABSTRACT Age and growth of Mediterranean slimehead, Hoplostethus mediterraneus in the Ionian Sea, Greece, were studied and morphometric relationships of otolith morphological characteristics were established, based on samples collected in 1996-1997. The length-weight relationships were positively allometric (sexes separately and combined). A strong correlation was found between total length (TL) and otolith weight, with the morphological characteristics of the otoliths (i.e., length, diameter, width and perimeter). The maximum age recorded, based on otolith reading, was nine years, for a female individual of TL of 22.2 cm, while males reached a maximum age of six years (TL=19.9 cm). Five different growth models were compared: the von Bertalanffy growth function (VBGF), the generalized VBGF, the Gompertz model, the logistic model, and a power model. The VBGM and Gompertz had substantial support by the data of female growth, while Gompertz and the logistic model were substantially supported for the growth of males. With the combined sexes, three models had substantial support: VBGF, generalized VBGF, and Gompertz. The model-averaged asymptotic length of H. mediterraneus was estimated (point estimate and 95% confidence interval in parentheses): 22.5 cm (20.9 – 24.0), 22.0 cm (16.0 – 28.1) and 23.6 cm (21.4 – 25.8), for females, males, and combined sexes respectively. The estimated parameters of the von Bertalanffy equation for both sexes -1 combined were: L∞=23.9 cm, K = 0.242 year , and t0= -1.39 years, whereas for the two sexes separately were -1 -1 estimated as: L∞=24.2 cm, K= 0.241 year , t0= -1.32 years, and L∞=23.2 cm, K= 0.244 year , t0= -1.52 years, for females and males respectively. INTRODUCTION Deep-sea fishes have been in the centre of scientific interest during the past few decades, as it is widely acknowledged that they comprise very sensitive stocks, mainly due to their high longevity, and low growth rates and reproduction outputs (e.g. Clark 2001). Their study has been made feasible due to technological enhancement related to sampling ability in greater depths, combined with economic aspects