Skip to main content
Ken  Leber
  • Sarasota, Florida, United States
  • Kenneth M. Leber, Mote Marine Laboratory Associate Vice President of Research, and University of Florida Courtesy Pro... moreedit
In designing research programs, scientists may constrain development of sequential hypotheses because of perceptions about logistical constraints to us-ing new technologies in monitoring or experimental design. Using trusted, familiar... more
In designing research programs, scientists may constrain development of sequential hypotheses because of perceptions about logistical constraints to us-ing new technologies in monitoring or experimental design. Using trusted, familiar methods can supersede asking which hypotheses would have the greatest impact and what method(s) are required to test them. To help maintain a 'problem-oriented' approach, rather than a 'methods oriented' one, we could strive to keep more aware of new innovations and applications in research; this is particularly so for tagging technology, when new methods emerge. Research enabled by recent innovations can be incorporated through collaborations with other scientists or by working di-rectly with vendors to implement and refine new tag technologies and applications. Some tagging studies can be improved by using multiple marking methods (e.g. see recent applications of various tag technologies with common snook Centropomus undecimalis and r...
Research Interests:
Page 1. 452 Abstract.-Declines in world fish-ery landings have prompted new inter-est in the use ofcultured fishes to help replenish depleted fish populations. The hypothesis that hatchery releases can increase population size ...
... A responsible approach to marine stock enhancement requires that potential negative impacts upon the gene pools of wild populations be mitigated through the use of genetically sound breeding and release protocols (Blankenship and... more
... A responsible approach to marine stock enhancement requires that potential negative impacts upon the gene pools of wild populations be mitigated through the use of genetically sound breeding and release protocols (Blankenship and Leber 1995). ...
Research Interests:
... Particular credit is due. though. to discussions with Lee Blankenship. Devin Bartley. Johann Bell. Ray Buckley. ... Ziemann. DA. Friedlander. A. and Cantrell. B.(2002) Carrying capacity for hatch-ery-reared Pacific threadfin... more
... Particular credit is due. though. to discussions with Lee Blankenship. Devin Bartley. Johann Bell. Ray Buckley. ... Ziemann. DA. Friedlander. A. and Cantrell. B.(2002) Carrying capacity for hatch-ery-reared Pacific threadfin (Polydactylus sexfllis) in native nursery habitats in Hawaii. ...
By the late 1980’s, following a century of stocking marine fishes to augment fisheries, not a single peer-review journal article had been published on the effects or effectiveness of stocking fishes that spawn in seawater. But by two... more
By the late 1980’s, following a century of stocking marine fishes to augment fisheries, not a single peer-review journal article had been published on the effects or effectiveness of stocking fishes that spawn in seawater. But by two decades later, science had grown rapidly in the field of marine fisheries enhancement. This was stimulated in large part by emerging new marine fish culture and tag technologies, experience gained in salmonid fisheries enhancement, and augmented by the publication in AFS Symposium 15 of a prescription for a science-based and responsible approach. Here we present the genesis, evolution and heuristic value of the Responsible Approach to marine stock enhancement, and show how awareness of it has fostered gains in the science underlying use of hatcheries in fisheries management worldwide and accomplishments made by incorporating such principles into stocking programs.
Marine fisheries enhancement (aka “stock enhancement”) is the use of hatchery-reared saltwater organisms to increase abundance and fishery yields in the wild. “Conservation hatcheries” also produce and stock depleted, threatened, or... more
Marine fisheries enhancement (aka “stock enhancement”) is the use of hatchery-reared saltwater organisms to increase abundance and fishery yields in the wild. “Conservation hatcheries” also produce and stock depleted, threatened, or endangered organisms – to help preserve species in decline. The practice began in the latter part of the nineteenth century when fish hatcheries were first developed but understanding of the ecology and management of wild stocks into which the hatchery-reared organisms where released was very limited. Early stock enhancement thus has gone through a series of fits and starts and misfires. In the century after its birth, the technologies required for scientific inquiry of the effects and effectiveness of stocking hatchery-reared organisms were lacking. The science needed to guide reliable use of cultured aquatic organisms in conservation and resource management remained undeveloped. Then, at the close of the twentieth century, new mariculture, tagging, and...
[NOTE: Originally published in 1995 in American Fisheries Society Symposium 15: 376-387] Declining marine fish populations worldwide have rekindled an interest in marine fish enhancement. Recent technological advances in fish tagging and... more
[NOTE: Originally published in 1995 in American Fisheries Society Symposium 15: 376-387] Declining marine fish populations worldwide have rekindled an interest in marine fish enhancement. Recent technological advances in fish tagging and marine fish culture provide a basis for successful hatchery-based marine enhancement. To ensure success and avoid repeating mistakes, we must take a responsible approach to developing, evaluating, and managing marine stock enhancement programs. A responsible-approach concept with several key components is described. Each component is considered essential to control and optimize enhancement. The components include the need to (1) prioritize and select target species for enhancement; (2) develop a species management plan that identifies harvest opportunity, stock rebuilding goals, and genetic objectives; (3) define quantitative measures of success; ( 4) use genetic resource management to avoid deleterious genetic effects; (5) use disease and health ma...
The state of Florida is seeking to expand its marine hatchery program for fisheries enhancement and conservation purposes. As part of this effort, a systematic process is being designed and implemented to prioritize candidate stocks for... more
The state of Florida is seeking to expand its marine hatchery program for fisheries enhancement and conservation purposes. As part of this effort, a systematic process is being designed and implemented to prioritize candidate stocks for hatchery production and fisheries enhancement. The aim of this process is to identify stocks in which release of hatchery fish is likely to serve fisheries enhancement and/or conservation goals. Prioritization of candidate stocks is based on a broad set of criteria, including quantitative modeling of the enhanced fisheries based on stock assessments, likely ecological and genetic impacts on wild components of target and interacting non-target stocks, aquaculture capability or potential and cost-benefit considerations. The process involves five phases: (1) an initial workshop, where selection criteria are defined and assigned weights; (2) a stakeholder survey to solicit opinions on the selection criteria and generate a consolidated list of candidate s...
The concept that depleted populations of marine fishes can be revitalized by releasing cultured fish is being tested in Hawaii. In this study we evaluated effects of interaction between release season and size-at-release on recapture... more
The concept that depleted populations of marine fishes can be revitalized by releasing cultured fish is being tested in Hawaii. In this study we evaluated effects of interaction between release season and size-at-release on recapture rates of cultured striped mullet, Mugil cephalus, released into Kaneohe Bay, Hawaii. Over 90,000 cultured M. cephalus fingerlings, ranging in size from 45 to 130 mm total length, were tagged with binary coded-wire tags. Half were released in spring, the remainder in summer. In both seasons, releases were made in three replicate lots. In each replicate, five size intervals of fish were released at two nursery habitats in Kaneohe Bay. Monthly cast-net collections were made in 6 nursery habitats over a 45-week period to monitor recapture rates, growth, and dispersal of cultured fish. Recapture rate was directly affected by the seasonal timing of releases. Greatest recovery of the smallest fish released (individuals <60 mm) occurred following spring rele...
Abstract: Project goals: To evaluate options for large-scale Diadema restoration and support management decision making through quantitative population modeling; and to develop and refine procedures for rearing large numbers of Diadema... more
Abstract: Project goals: To evaluate options for large-scale Diadema restoration and support management decision making through quantitative population modeling; and to develop and refine procedures for rearing large numbers of Diadema for restoration research ...
ABSTRACT In this study, an integrative review of the potential for stock enhancement is conducted to support desirable management outcomes in marine recreational fisheries, focusing on the Florida, USA, red drum fishery as a case study.... more
ABSTRACT In this study, an integrative review of the potential for stock enhancement is conducted to support desirable management outcomes in marine recreational fisheries, focusing on the Florida, USA, red drum fishery as a case study. Here, stock enhancement is implicitly seen as a way of simultaneously achieving both ecological objectives of sustained wild fish populations and socioeconomic objectives of high fishing effort and/or catch rates. However, the review suggests that a fundamental tradeoff remains between these objectives in the short-term because stocking of hatchery fish is likely to result in at least partial displacement of wild fish through biological interactions as well as increased fishing pressure. Contrary to the perception of enhancement as a "quick fix," successful use of the approach in the marine recreational fishery is likely to require sophisticated stock management and some adaptation in governance. In developing the enhancement, it will be necessary to address uncertainty in key attributes, specifically dynamics of recruitment, angler-effort responses, and stakeholder involvement. This may be achieved by combining quantitative modeling, monitoring, and stocking experiments in an active adaptive management framework to consider enhancement in the context of alternative management strategies. It is suggested that any interim enhancement should minimize ecological risk per socioeconomic benefit by stocking larger fish in areas where high fishing mortality limits abundance of wild fish. These conclusions are largely generalizable to other recreational enhancements, and this work serves as a model of rarely published a priori enhancement evaluation.
ABSTRACT Rigorous assessment of species and ecosystem biology underpins responsible marine stock enhancement. Estimation of limits to stocking density, based on ecosystem productivity and energetic requirements of stocked species, can be... more
ABSTRACT Rigorous assessment of species and ecosystem biology underpins responsible marine stock enhancement. Estimation of limits to stocking density, based on ecosystem productivity and energetic requirements of stocked species, can be used to gauge the appropriate magnitude of release densities, minimizing waste of resources, and the possibility for adverse stocking effects. A generalized mass-balance model (generalized predatory impact model) for stocking density estimation has been developed. The approach is based around the principles of ECOPATH and accounts for dynamic estimation of stocking-related ecosystem relationships at fine temporal (days) and spatial scales. The main parameter inputs include probability distributions for key biological and life-history traits of stocked species and estimates of primary productivity for the target ecosystem. The energetic requirements of stocked fish are evaluated in terms of growth and mortality as well as ontogenetic transitions in diet, habitat use, morphology, and migration. The theoretical carrying capacity for a stocked species within a given arena is assessed from primary productivity, levels of predation by stocked fish on different trophic groups, and a specified level of acceptable trophic impact. A Monte Carlo analysis of uncertainty is used to provide a probability distribution of stocking densities for a given trophic impact. The model is applied for stocking juveniles of snook (Centropomus undecimalis) in Sarasota, FL, USA, and mulloway (Argyrosomus japonicus) in Georges River, NSW, Australia. The model is useful for estimating an appropriate stocking density when planning pilot-scale fish releases. Such releases should be carefully monitored to validate model assumptions and determine density-dependent and other environmental effects.
Page 1. Fisheries Management and Ecology 1996, 3, 261-278 Stock enhancement in a commercial mullet, Mugil cephalus L., fishery in Hawaii KM LEBER & SM ARCE The Oceanic Institute, Makapuu Point, Waimanalo, Hawaii, USA ...
This research was designed (1) to examine the role of predatory decapod crustaceans as an organizing force in prey distribution and abundance patterns, and (2) to compare the importance of vegetation as a prey refuge from predators with... more
This research was designed (1) to examine the role of predatory decapod crustaceans as an organizing force in prey distribution and abundance patterns, and (2) to compare the importance of vegetation as a prey refuge from predators with its importance as a ...
... Petersburg, Florida 33701 PRINCIPAL INVESTIGATOR Carole Neidig, MS PROJECT MANAGERS: Carole Neidig, MS - Ken Leber, Ph.D. CONTRIBUTORS: Carole Neidig, MS - Dario Varga, BA-Sondra Graves, BS Dan Roberts, BS (FWC, FMRI) ...
... On each sampling date eight scrape and four trawl tows were taken (in the se-quence two trawls, eight scrapes, two trawls) dur-ing the day, and again beginning 1 h after dark. ... 4 0.032 L/binia dubia 5 0.048 4 0.088 CfInt1oprfstJ8... more
... On each sampling date eight scrape and four trawl tows were taken (in the se-quence two trawls, eight scrapes, two trawls) dur-ing the day, and again beginning 1 h after dark. ... 4 0.032 L/binia dubia 5 0.048 4 0.088 CfInt1oprfstJ8 msIana 3 0.106 ...
Seasonal changes in macrobenthic community structure on a temperate, western Atlantic, high energy beach were examined over a IS-month period during 1976and 1977. Twelve macroinvertebrate species were collected from the intertidal and... more
Seasonal changes in macrobenthic community structure on a temperate, western Atlantic, high energy beach were examined over a IS-month period during 1976and 1977. Twelve macroinvertebrate species were collected from the intertidal and nearshore surf zones ...
... Kai Lorenzen, Robert S. Steneck, Robert R. Warner, Ana M. Parma, Felicia C. Coleman, and Kenneth M. Leber ... Most importantly, it can foster the emergence of sustainable, rights-based governance regimes and protected areas to aid... more
... Kai Lorenzen, Robert S. Steneck, Robert R. Warner, Ana M. Parma, Felicia C. Coleman, and Kenneth M. Leber ... Most importantly, it can foster the emergence of sustainable, rights-based governance regimes and protected areas to aid conservation and restoration of marine ...
... 389 RECRUITMENT PATTERNS OF CULTURED JUVENILE PACIFIC THREADFIN, POLYDACTYLUS SEXFILIS (POLYNEMIDAE), RELEASED ALONG SANDY MARINE SHORES IN HAWAII ... The species is a marine carnivore. Juveniles prefer inshore, sandy marine habitats.... more
... 389 RECRUITMENT PATTERNS OF CULTURED JUVENILE PACIFIC THREADFIN, POLYDACTYLUS SEXFILIS (POLYNEMIDAE), RELEASED ALONG SANDY MARINE SHORES IN HAWAII ... The species is a marine carnivore. Juveniles prefer inshore, sandy marine habitats. ...
Reviews in Fisheries Science 21(3-4):213-221 (2014). Aquaculture-based enhancement of marine fisheries includes sea ranching, stock enhancement, and restocking. A rapidly evolving context and maturing science base have effectively put... more
Reviews in Fisheries Science 21(3-4):213-221 (2014). Aquaculture-based enhancement of marine fisheries includes sea ranching, stock enhancement, and restocking. A rapidly evolving context and maturing science base have effectively put these approaches into the fisheries management toolbox. Among the contextual factors are (1) a rapid expansion of captive breeding and domestication to new marine species, (2) fisheries governance systems that address the common dilemma, and (3) global environmental change impacts on coastal fisheries that increasingly call for active approaches to maintaining or increasing fisheries yields and ecosystem services. The science base of marine restocking, stock enhancement, and sea ranching continues to advance rapidly and has now reached a point where it is becoming possible to assess the likely contribution of such approaches to fisheries management goals prior to major investments being undertaken and to design enhancement programs effectively and responsibly where good potential is judged to exist. This signifies an important transition of marine fisheries enhancement from an exploratory, research-oriented endeavor to a tool in the fisheries management tool box.
Research Interests:

And 11 more