Mote Marine Laboratory

Links to current research projects

Snook Shindig08

Snook ponds

Snook Stock Enhancement

Research Interests:
Much of my work at Mote, is focused on studying the efficacy of marine stock enhancement as a supplementary management tool. Using releases of hatchery-reared organisms (within scientifically rigorous and carefully controlled experimental applications) can aid in our understanding, for example, of recruitment dynamics, density-dependence, habitat influence on growth and survival, and when and where ontogenetic habitat shifts might occur. With snook, I've been involved in testing many of these issues including (1) developing cost-effective, reliable, and benign tagging systems, (2) evaluating various release strategies to improve stocking efficiency and post-release survival, (3) understanding and quantifying the influence of various rearing habitats on post-release survival and growth, (4) understanding effects of stocking hatchery-reared juveniles on wild conspecifics (such as through competition and predation for shared resources), and (5) quantifying the production of various rearing habitats to adult stages of snook.

I have experience performing related work with red drum (Scianops ocellata), red snapper (Lutjanus campechanus), striped mullet (Mugil cephalus), and moi (Pacific Threadfin) (Polydactlus sexfilis).

Tagging: Adapting tag technology is an integral component in understanding the effects of stock enhancement activities on both stocked and wild fish. A benign tag, easily and quickly applied to small fishes with a high information content is what we are striving toward. Currently, we are primarily using the coded-wire tag (CWT) and the visible implant elastomer (VIE), developed by Northwest Marine Technology, which facilitates large-scale tagging of fingerling fishes. While the CWT has high information content, it's internally implanted and generally undetectable without a magnetic sensor.Therefore, we are researching the use of VIE tags to serve as external indicators of hatchery-reared fish in the wild (see picture of VIE material in snook caudal fin). I am also testing the use of colored VIE tags for underwater assessment of red snapper on artificial reefs. By varying tag color and body location we (SCUBA divers) are able to passively identify the treatments of our experiments without harming or handling the fish.We are also conducing research with sonic (VEMCO), and PIT (Biomark Inc.) tags in our study species.

Other Research Interests
Population/Stock Assessment; ecological models; essential fish habitat; habitat restoration; spawning behavior; diurnal and nocturnal behavioral variations; interspecific interactions; annual migration; ontogenetic habitat shifts; database management; aquacutlure and recirculating systems.

Ph.D. Fisheries University of Florida, Department of Fisheries and Aquatic Sciences, Gainesville, Florida. Dissertation Title: HABITAT AND DENSITY-MEDIATED INFLUENCES ON SNOOK ECOLOGY: LESSONS LEARNED FROM MANIPULATIVE RELEASE EXPERIMENTS WITH HATCHERY-REARED JUVENIEL SNOOK. <Abstract> Doctoral committee co-chairs: W.J. Lindberg and K.M.Leber

M.S. Biology Tennessee Technological University, Cooperative Fisheries Research Unit, Cookeville, Tennessee. Thesis: "Establishment and Management of a Multi-State Paddlefish Coded-wire Tag Database" <Abstract> Major Professor: Phillip W. Bettoli.

B.A. Zoology University of Hawaii, Zoology. Emphasis in field biology and zoology, especially ornithology. Research projects included surveys of endemic bird populations at Hakalau Research Station on Mauna Kea, Hawaii. Included point counts, mist netting, and health checks of captured birds. Also conducted a research project on the red footed booby population in Ulupau Crater, Oahu. Included observations on mating behavior, stomach contents, and parental care of young.

Marine Stock Enhancement

Brennan, N.P., C.J. Walters, and K.M. Leber. 2008. Manipulations of stocking magnitude: addressing density dependence in a juvenile cohort of Common snook (Centropomus undecimalis). Reviews in Fisheries Science, 16(1-3): 215-227. [pdf file]

Brennan, N.P., K.M. Leber, and B.R. Blackburn. 2007. Use of coded-wire and visible implant elastomer tags for marine stock enhancement of juvenile red snapper Lutjanus campechanus. Fisheries Research 83: 90-97. [PDF file]

Brennan, N.P., M.C. Darcy, and K.M. Leber. 2006. Predator-free enclosures improve post-release survival of stocked common snook. Journal of Experimental Marine Biology and Ecology 335 (2): 302-311. [PDF file]

Brennan, N.P., K.M. Leber, H.L. Blankenship, J. Ransier, and R.DeBruler Jr.. 2005. An evaluation of coded-wire and elastomer tag performance in juvenile snook under field and laboratory conditions. North American Journal of Fisheries Management 25:437-445. [PDF file]

Leber, K. M., N. P. Brennan and S. M. Arce. 1998. Recruitment patterns of juvenile, cultured Pacific threadfin, Polydactylus sexfilis (Polynemidae), released along sandy marine shores in Hawaii. Bulletin of Marine Science 62(2):389-408. [PDF file]

Leber, K.M., H.L. Blankenship, S.M. Arce, and N.P. Brennan. 1997. Influence of release season on size-dependant survival of cultured striped mullet, Mugil cephalus, in an Hawaiian estuary. Fishery Bulletin 95(2):267-279. [PDF file]

Leber, K.M., S.M. Arce, D.A. Sterritt, and N.P. Brennan. 1996. Marine enhancement potential in nursery habitats of striped mullet, Mugil cephalus, in Hawaii. Fishery Bulletin 94(3): 452-471. [PDF file]

Leber, K.M., N.P. Brennan, and S.M. Arce. 1995. Marine enhancement with striped mullet: are hatchery releases replenishing or displacing wild stocks? In: H.L.Schramm Jr. and R.G.Piper (editors), Uses and effects of cultured fishes in aquatic ecosystems, pp.376-387. American Fisheries Society Symposium 15. [PDF file]

Database Management

Brennan, N.P. 1997. Establishment and management of a multi-state paddlefish coded-wire tag database. Masters Thesis. Tennessee Technological University. Cookeville, TN 38505

Department: Directorate of Fisheries & Aquaculture