Population estimation and female reproductive state of spiny dogfish (Squalus acanthias) overwintering in North Carolina coastal waters / by Kelly Elizabeth Register.
| Author/creator | Register, Kelly Elizabeth author. |
| Other author | Rulifson, Roger A. (Roger Allen), 1951- degree. |
| Other author | East Carolina University. Department of Biology. |
| Format | Theses and dissertations |
| Production | 2006. |
| Description | xii, 89 leaves : illustrations, maps ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Subject | The spiny dogfish (Squalus acanthias) shark supported a significant North Carolina winter fishery in the late 1980s and early 1990s, but in 1998 was declared overfished by the National Marine Fisheries Service (NMFS); a subsequent Spiny Dogfish Fishery Management Plan (FMP) was implemented by the U.S. Secretary of Commerce. The goal of my study was to determine whether the population demographics of the spiny dogfish population overwintering in North Carolina coastal waters have changed since implementation of the FMP. In 2006 I examined the overwintering population of spiny dogfish to produce an estimate of population size (both Schnabel and area-density experiments); determine the male-female ratio; establish length at 50% maturity for females (L₅₀); calculate the pup size-maternal size relationship; and determine fecundity. A Schnabel mark-recapture estimate conducted from the Virginia line to Cape Hatteras, and an area-density estimate conducted from the Virginia line to Ocracoke Inlet using commercial fishing practices and systematic sampling scheme gave similar estimates, 28,979,092 ± 7,613.03 and 34,801,164 individuals, respectively. Commercial fishing practices were used from Cape Hatteras to Ocracoke Inlet to produce area-density and mark-recapture population estimates of an aggregation. The two methods produced estimates of 899,674 ± 948.51 and 6,898,975 individuals, respectively. Maturity and fecundity studies on 346 female subsampled during the population study suggest that L₅₀ (L₅₀ = 81.1 cm) and fecundity are returning to previously stable levels reported in previous research. There was a positive correlation between number of pups and female size. There was no relationship between pup size and maternal size of all pups. However, there was a positive correlation between the size of pups in the latest stage of development (late Stage V) and maternal size. The relationship between maternal size and fecundity shows that large females produce the most pups, and these pups may be larger than the pups of smaller females, which could increase survivability. This information indicates that a targeted North Carolina spiny dogfish fishery has the potential to overexploit large females. If these large females are overharvested it could cause another stock crash. |
| General note | Presented to the faculty of the Department of Biology. |
| General note | Advisor: Roger A. Rulifson |
| Dissertation note | M.S. East Carolina University 2006 |
| Bibliography note | Includes bibliographical references (leaves 49-52). |
| Genre/form | dissertations. |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
Availability
| Library | Location | Call Number | Status | Item Actions |
|---|---|---|---|---|
| Joyner | University Archives | ASK AT SPECIAL COLLECTIONS DESK | ✔ Available | Request Material |
| Electronic Resources | Access Content Online | ✔ Available |