LEADER 00000nam  2200385   4500 
001    AAI3511747 
005    20121124142202.5 
008    121124s2012    ||||||||||||||||| ||eng d 
020    9781267398840 
035    (UMI)AAI3511747 
040    UMI|cUMI 
100 1  Deleveaux, Vallierre K. W 
245 10 On the growth and exploitation pattern effects on the 
       recuperation from overfishing of the red snapper, Lutjanus
       campechanus, in the Gulf of Mexico 
300    131 p 
500    Source: Dissertation Abstracts International, Volume: 73-
       10, Section: B, page:  
500    Adviser: Nelson M. Ehrhardt 
502    Thesis (Ph.D.)--University of Miami, 2012 
520    Due to the very long history of high exploitation levels 
       in the red snapper fishery (>130 yrs) there was a need to 
       assess whether the minimum size regulations were serving 
       their intended purpose of protecting the spawning stock, 
       reducing the probability of recruitment failure and 
       increasing the yield from the stock. To meet this 
       objective a good descriptor of red snapper growth was 
       required in order to simulate the existent exploitation 
       pattern of the gears involved in the fisheries. An 
       extensive analysis of red snapper growth was conducted 
       using data supplied by the National Marine Fisheries 
       Service (NMFS) Panama City, Florida Laboratory. The data 
       set (database 1 (DB1)) contained information on otolith 
       ageing and the annuli measurements made along the dorsal 
       side of the sulcus acousticus as well as total length 
       measurements collected from 370 fish between age 2 and 17.
       Data for the previous growth studies on red snapper, which
       were collected from the directed fisheries, indicated an 
       underrepresentation of several age categories of fish. Due
       to the selectivity of the gears a major portion of the age
       two fish and even possibly some segment of the age three 
       fish (smaller, slow-growing individuals) were not included
       in the data collection, therefore it is necessary to 
       ensure that proportionality exists between the otolith and
       somatic growth. The results of the analysis here indicated
       that the back-calculated otolith radius-total length 
       measurements were uncoupled for several age classes, 
       meaning that the growth in total length was not 
       proportional to the otolith growth in all age classes. 
       This, therefore, indicated that the data was not suitable 
       for providing a good descriptor of the growth of the red 
       snapper when used in back-calculations of size-at-age 
520    Several back-calculation models were selected to generate 
       growth function parameters for comparison purposes. These 
       models included several multiple regression models, the 
       age-effects model (Morita & Matsuishi, 2001), a log-power 
       model (Ehrhardt, 1992) and the Modified Fry model 
       (Vigliola & Meekan, 2009). The result of each model was 
       tested by comparing the mean of the observed lengths-at-
       age to the mean of the back-calculated lengths-at-age. It 
       was found that all of the models used approximated the 
       observed data as there was no significant difference 
       between the observed mean lengths-at-age and the back-
       calculated mean-lengths-at-age at the 0.05% level 
520    Next, how well the age structure of the samples 
       represented the stock was investigated. It was found that 
       the age two fish were underrepresented due to the 
       selectivity of the fishing gears. Also, the larger and 
       older fish in the size-at-age distributions were mostly 
       absent, perhaps also due to fishing gear selectivity and 
       the resulting exploitation pattern (Walter & Ingram, 
       2009). This problem was approached by treating the age two
       and the older age classes as containing missing data, 
       which would suggest a slower growth rate for smaller fish 
       and perhaps a larger maximum size for older fish. A Monte 
       Carlo approach was used to generate experimental length-at
       -age data from the Modified-Fry model which would then be 
       used to simulate an unbiased virgin red snapper length-at-
       age population structure based on the results of the 
       Modified Fry model 
520    Finally, to evaluate the appropriateness of the use of 
       minimum size in the management framework to recuperate the
       red snapper stock it was necessary to consider the life 
       history, the fishing mortalities due to the shrimp fishery,
       to the discards below the minimum size and to the closed 
       season discards, and the temporal distribution of the fish
       stock.  Several management scenarios, different minimum 
       sizes under different levels of shrimp bycatch, were 
       investigated that estimated the likelihood of red snapper 
       recuperation to the management goal of 20% SPR by 2032. 
       The results indicated that only in the complete absence of
       any shrimp fishery bycatch would the SPR approach 18.5%, 
       still short of the goal, regardless of any minimum size 
       selected. At the target 50% shrimp bycatch reduction level
       the SPR is only projected to increase to about 7.2%, 
       regardless of the minimum size implemented. These results 
       show the minimum size regulations to be ineffective in 
       meeting their intended goal of protecting the spawning 
       stock for red snapper in the Gulf of Mexico.  (Abstract 
       shortened by UMI.) 
590    School code: 0125 
650  4 Agriculture, Fisheries and Aquaculture 
690    0792 
710 2  University of Miami.|bMarine Biology and Fisheries 
       (Marine) 
773 0  |tDissertation Abstracts International|g73-10B 
856 40 |uhttp://pqdd.sinica.edu.tw/twdaoapp/servlet/
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