Trying to manage a fish population is an endeavor with several factors, both known and unknown. Currently, there is a big push for the better understanding and management of Long-Lived fish populations. These populations are hard to study and harder to manage because there is so little known about them and how to manage a k strategist (an individual that focuses onXXXX). The Yelloweye Rockfish (Sebastes ruberrimus) is a k strategist species of fish that lives on the Pacific Coast ranging from California to Alaska. The lower populations of this rockfish are showing signs of overharvesting and habitat destruction, the population located in Puget Sound (Washington) has been listed as “Threatened” by the National Oceanic and Atmospheric Administration. This population is currently protected and unless a management procedure is implemented it is likely the population will be lost. The Yelloweye brings several obstacles to management efforts; their inability to be brought to surface and survive due to barotrauma (XXXX) makes it hard to protect the species from mortality due to by catch (xxxx). Their longevity (xxxx) and delayed sexual maturity (xxxx) make it highly difficult to get the population to successfully reproduce; with an estimated age of sexual maturity around 20 years old, it is hard to ensure survival of the offspring without directly controlling it. Thus, it would be highly productive for the scientific community to understand how to manage k-strategist since most of them are easily overharvested and recover poorly from fishing efforts.
Purpose of the Study
The purpose of this study is to better understand how to manage a long-lived marine species. There are several goals that are accomplished by successfully design a management method for the Yelloweye Rockfish. These goals include reviving the threatened Yelloweye population in Puget Sound, study the benefits of hybridization in k-strategists, and increase the ecosystem health of Puget Sound by improving water quality, habitats, and increasing species richness (the number of species found in a habitat; the higher the number, the more diverse the habitat is and the healthier the ecosystem is).
Back-Cross – “The mating of a hybrid organism (offspring of genetically unlike parents) with one of its parents or with an organism genetically similar to the parent.”
Barotrauma– The expansion of the air-filled swim bladder during ascent that may result in injury or death of the fish.
Critical Habitat– “A specific geographic area(s) that contains features essential for the conservation of a threatened or endangered species and that may require special management and protection”
Fitness– An individual’s ability to reach sexual maturity, locate a mate, and produce viable offspring.
Hybridization– “ The process of interbreeding between individuals of different species (interspecific hybridization) or genetically divergent individuals from the same species (intraspecific hybridization). Offspring produced by hybridization may be fertile, partially fertile, or sterile.”
Introgression– “Back-cross of a hybrid individual with one of its progenitors (parent or ancestor)”
Iteroparity-An individual that can reproduce multiple times in one lifetime.
K-selected traits– Long adult lifespan, delayed maturity, ability to reproduce multiple times in a life, traits that maximize fitness when resources are scarce but somewhat constant, much like they are when the population is at carrying capacity (K).
Marine Reserves-Protected areas of the ocean where there is no killing, harming, or harassing of any plants or animals permitted
Slot-limits– A size limit for a species that limits the minimum and maximum size that the fish can be, thus it must be able to fit in the given slot.
Significance of the Investigation
By properly managing the Yelloweye Rockfish population the methods used can be implemented onto similar cases of k-strategist species that may be currently suffering a population decline. Commercial fishing is on the rise and is one of the lead reasons that k-strategist populations are on the decline. K-strategist species are evolved to survive at a population maximum for their ecosystem, their longevity and delayed sexual maturity is a way to keep their population from surpassing the carrying capacity (the maximum number of individuals in a species that can survive in an ecosystem, usually nutrient dependent) of their ecosystem and causing a population collapse. This strategy is detrimental when a population is being harvested faster than it can reproduce and thus it is r-strategists that can better survive high levels of harvesting. Thus, there are several species that are currently in a population decline and because they naturally occur at the carrying capacity they appear to be abundant and unaffected by fishing practices when truly populations are rapidly declining and, unless they are protected and managed, will be lost in the near future.
Managing Long-lived marine species is not in the forefront of science currently, as stated earlier, many populations are on the decline but are yet to reach threatened levels and are thus not a current concern for scientists. The best compilation of papers relating to conservation and management of long-lived species is “Life in the Slow Lane: Ecology and Conservation of Long-Lived Marine Animals” compiled by J.A. Musick. The three articles in this book that I focused on were: “Ecology and conservation of long-lived marine animals,” “Management of Long-Lived Marine Resources: A Comparison of Feed back-Control Management Procedures,” and “Management and conservation of temperate reef fishes in the grouper-snapper complex of the southeastern United States.” These three articles came to similar conclusions, current management methods implemented on non-long-lived species will not work on long-lived species, k-strategists are more susceptible to collapsing due to over fishing, and the best way to protect these species is to make their critical habitats marine reserves (areas that it is illegal to kill, harm, or harass life).
Looking at more non-contemporary aspects of conservation of species I have decided to bring in hybridization. Hybridization (the crossing of two species to create a new species) is a controversial practice and if not for the success it has had I would not include it in this study. Dr. Andrew Martin of University of Colorado Boulder has been involved in several hybridization projects to help preserve species that are on the brink of extinction. His work with the Devils Hole Pupfish and the Greenback Cutthroat Trout were vital to increasing population size, species richness, and genetic flow in small inbred populations. Two papers that he was involved in (“Hybridization Dynamics between Colorado’s Native Cutthroat Trout and Introduced Rainbow Trout” and “Dramatic shifts in the gene pool of a managed population of an endangered species may be exacerbated by high genetic load”) provide evidence for the success of hybridization. It is my hope that by crossing the Yelloweye Rockfish with a shorter lived rockfish there may be a decrease in longevity and an increase in fecundity, there have been instances of other Rockfish hybridizing naturally (assessed by Piper Schwenke in her Master’s thesis “History and extent of introgressive hybridization in Puget Sound rockfishes (Sebastes auriculatus, S. caurinus, and S. maliger)”). Thus, with such high success rates in other areas and naturally amongst rockfish I feel that there will be a high chance of success for this to aid in reestablishing the Yelloweye Rockfishes population.
Thesis and questions
The Yelloweye Rockfishes (Sebastes ruberrimus) population maybe successfully managed and returned to historical populations size via a combination of habitat restoration, importation of Yelloweye Rockfish from other healthy localities, hatcheries, hybridization, marine reserves, and educating the public on conservation. I believe this multistep plan will allow for successful management of the species, and by spreading out the efforts into multiple parts it increases the likelihood that the Yelloweye population will respond to one of the methods. There are several unknowns in this study, the biggest question is can the Yelloweye hybridize and if so will it help increase the fecundity of the population? It is also important to ask if the niche that the Yelloweye typically fills has been taken over by another species, thus making it harder for the population to take hold in the given habitat. Finally, if these methods of management are successful, can they be implemented on other long-lived species that are experiencing a decline in population size?