동해에서 수온이 명태(Gadus chalcogrammus) 초기생활사에 미치는 영향
Effects of water temperature changes on the early life stages(egg & larvae) of walleye pollock(Gadus chalcogrammus) in the East Sea
- 저자식별ID ORCID:0000-0002-9437-098X
- 주제(키워드) 도움말 명태 , 초기생활사 , 생존율 , 성장률 , 해양환경
- 발행기관 강릉원주대학교 일반대학원
- 지도교수 도움말 이충일
- 발행년도 2022
- 학위수여년월 2023. 2
- 학위명 석사
- 학과 및 전공 도움말 일반대학원 해양생태환경학과
- 세부분야 해당없음
- 실제URI http://www.dcollection.net/handler/kangnung/000000011338
- UCI I804:42001-000000011338
- 본문언어 한국어
초록/요약 도움말
In the Korean waters, walleye pollock (Gadus chalcogrammus) was distributed (hear after pollock) over a wide range from the southeastern coast of the Korea (Pohang) to the middle eastern coast of Korea (Goseong) until the mid-1980s, after that, the amount of catch and the area of fishing grounds have decreased rapidly. Since the mid-2000s, the annual catch of pollock is about 1 ton, and it is caught intermittently on the middle eastern coast of Korea. Overfishing of immature pollocks and climate changes are reported as the causes of such pollock stock decline. However, the effects of these factors have not been clearly explained due to a lack of relevant data. In this study, we hypothesized that changes in water temperature would affect the hatching rates and periods of fertilized eggs, and the growth and survival of larvae. In the lab experiment, the water temperature of the fish tank was set (3.6, 5.1, 7.1, 10.0, 13.3, 15.1℃), and the survival and growth of fertilized eggs and larvae at each temperature were analyzed, and seawater filtered through a membrane filter (0.45 ㎛) was used. The water temperature in each tank was based on the sea surface temperature distributed along the coast of the East Sea from December to March, the main spawning season for pollock. In each tank, the experiment was conducted continuously from fertilized eggs to the post-larvae stage, and based on the lab experimental results, the effects of changes in the surface water temperature along the eastern coast of Korea on the early life cycle of pollock were estimated. The fertilized eggs used in the experiment were eggs spawned at 7℃. The hatching rate and hatching period of fertilized eggs were inversely proportional to water temperature, the higher water temperature above 13℃ showed a higher rate of abnormal egg development. The hatching rate was the highest at 83% at 3.6℃. 50% at 10.0℃ and 4% at 15.1℃. The hatching period was the longest at 23 days at 3.6℃. 12 days at 10.0℃ and 6 days at 15.1℃. The average density (σt) of fertilized eggs was 20.8±1.3, and the density pre-hatching stages tended to increase to 23.9±0.6. The total length of larvae hatched at 3.6℃ was the largest at 5.14±0.05 mm, and the maximum growth length was also the longest. At 10.0℃, the larvae size was the smallest at 4.91±0.26 mm, and the maximum growth length was the smallest. The growth rate of larvae after hatching tended to be high in proportion to the water temperature, and the period of reaching the maximum growth was inversely proportional to the water temperature. The yolk volume of the larvae immediately after hatching was larger as the water temperature was higher, and the yolk sac absorption rate tended to be higher as the water temperature increased. Larvae showed a gradual decrease in length after maximum growth. 50% mortality rate of larvae was faster with higher water temperature. It was evaluated that the higher water temperature (≥ 10℃) affects the survival and growth of fertilized eggs and larvae as a result of the lab experiment. The water temperature isothermal line (10℃) in the early 1980s was formed on the southern part of the eastern coast of Korea during the pollock spawning season. However, after the mid-1980s, 10℃ isothermal lines moved northward to the middle eastern coast of Korea. It seems that the coastal environment in the southern part based on the middle coast of the east sea since the mid-1980s negatively affects the development, hatching, survival and growth in pollock early life stages based on the results of the lab experiment. This study will help to understand the impact of marine environment changes on the early life stages of pollock, and it will contribute that predicting pollock resource fluctuation to changes in the marine environment in the future.
more목차 도움말
목 차
List of Tables ⅰ
List of Figures ⅱ
Abstract ⅳ
Ⅰ. 서 론 1
Ⅱ. 재료 및 방법 7
1. 수정란
2. 실험 수조 환경
3. 난 부화기간, 부화율, 난경
4. 난 밀도
5. 자어 길이, 난황 부피, 생존율
6. 동해 연안 표층수온
7. 통계분석
Ⅲ. 결 과 15
1. 부화기간, 부화율, 난 발달과정
2. 난경, 난 밀도
3. 자어의 성장률과 난황 흡수율
4. 자어 생존율
5. 동해 연안 표층수온 장기 변화
Ⅳ. 고 찰 36
Ⅴ. 요 약 42
Ⅵ. 참고 문헌 43
Ⅶ. 부록 55
Ⅷ. 감사의 글 58
