Presentation is loading. Please wait.

Presentation is loading. Please wait.

Age and growth estimates of the winter skate (Leucoraja ocellata) in the western Gulf of Maine 西緬因灣眼斑鰩年齡與成長評估 James A. Sulikowski Michael D. Morin Seung.

Similar presentations


Presentation on theme: "Age and growth estimates of the winter skate (Leucoraja ocellata) in the western Gulf of Maine 西緬因灣眼斑鰩年齡與成長評估 James A. Sulikowski Michael D. Morin Seung."— Presentation transcript:

1 Age and growth estimates of the winter skate (Leucoraja ocellata) in the western Gulf of Maine 西緬因灣眼斑鰩年齡與成長評估 James A. Sulikowski Michael D. Morin Seung H. Suk W. Huntting Howell Fishery Bulletin.101:405–413 (2003). 指導教授 莊守正老師 指導教授 莊守正老師 學生 陳婧綺 學號 M 學號 M

2 Winter Skate Morphology Morphology Distribution Distribution Biology Biology © George Burgess

3 Morphology Disk rounded. Disk rounded. With many small dark spots on upper surface, usually 1-4 ocelli. With many small dark spots on upper surface, usually 1-4 ocelli. Young have long middorsal row of large spines on disk and tail. Young have long middorsal row of large spines on disk and tail. © James Sulikowski

4 Distribution Western Atlantic: Newfoundland Banks and southern Gulf of St. Lawrence in Canada to North Carolina, USA. Western Atlantic: Newfoundland Banks and southern Gulf of St. Lawrence in Canada to North Carolina, USA.

5 Biology Prefer sandy and gravelly bottoms in shoal water in the north range. Prefer sandy and gravelly bottoms in shoal water in the north range. Mostly inactive during daylight hours, but active under dark conditions. Mostly inactive during daylight hours, but active under dark conditions. Distinct pairing with embrace. Young may tend to follow large objects, such as their mother. Distinct pairing with embrace. Young may tend to follow large objects, such as their mother.

6 Introduction Little is known about the biology of many elasmobranchs’ life history. Little is known about the biology of many elasmobranchs’ life history. Difficulty in obtaining samples. Difficulty in obtaining samples. Recent assessment studies suggest that the biomass of the winter skate maybe below threshold-levels, mandated by the Sustainable Fisheries Act. Recent assessment studies suggest that the biomass of the winter skate maybe below threshold-levels, mandated by the Sustainable Fisheries Act.

7 To add insight into the life history of the species and the status of the stock, we estimated age and growth rates of L.ocellata by interpreting annular counts and marginal increments on vertebral centra from specimens collected in the western Gulf of Maine. To add insight into the life history of the species and the status of the stock, we estimated age and growth rates of L.ocellata by interpreting annular counts and marginal increments on vertebral centra from specimens collected in the western Gulf of Maine.

8 Materials and Methods Sampling Sampling period: November 1999 and May Sampling period: November 1999 and May Sampling amount: 304. Sampling amount: 304. Sampling site: New Hampshire’ coast. Sampling site: New Hampshire’ coast. Approximate depth: 9-107m. Approximate depth: 9-107m. Captured by otter trawl Captured by otter trawl Total length, disc width, and total wet weight were measured and recorded. Total length, disc width, and total wet weight were measured and recorded.

9

10 Preparation of vertebral samples Vertebral samples, taken from above the abdominal cavity, were removed from 230 winter skates (132 females and 98 males) labeled, and stored frozen. Vertebral samples, taken from above the abdominal cavity, were removed from 230 winter skates (132 females and 98 males) labeled, and stored frozen.

11 Counts of annuli

12 IAPE( 平均百分誤差指數 ) N= the number of skate aged N= the number of skate aged R= the number of readings R= the number of readings X ij = the ith age determination of the jth fish X ij = the ith age determination of the jth fish X j = the average calculated for the jth fish X j = the average calculated for the jth fish

13 Marginal increment analyses D: 椎徑 D: 椎徑 D n : 脊椎骨最外輪之輪 D n : 脊椎骨最外輪之輪 D n-1 : 脊椎骨次外輪之輪徑 D n-1 : 脊椎骨次外輪之輪徑 Kruskal-Wallis one-way analysis of variance on ranks was used to test for differences in marginal increment by month. Kruskal-Wallis one-way analysis of variance on ranks was used to test for differences in marginal increment by month.

14 Growth estimates A von Bertalanffy growth function (VBGF) was fitted to the data with the following equation (von Bertalanffy, 1938): where L t = total length at time t (age in years) L ∞ = theoretical asymptotic length L ∞ = theoretical asymptotic length k = Brody growth constant k = Brody growth constant t 0 = theoretical age at zero length (minus) t 0 = theoretical age at zero length (minus)

15 Results

16 Morphology measurements (mm)

17 Vertebral analyses

18

19 Age and growth estimates Males: L∞ = 1218 mm (TL). Females: L∞ = 1374 mm (TL). IAPE=5.8%

20 The oldest age estimates obtained for the winter skate were 19 and 18 years for males and females

21 Discussion The important of IAPE The important of IAPE The relationship between TL and centrum The relationship between TL and centrum diameter was linear and significant, indicating that the centra grew proportionally to skate length for all size classes, and thus this structure was useful for age analyses. diameter was linear and significant, indicating that the centra grew proportionally to skate length for all size classes, and thus this structure was useful for age analyses. Holden(1977), Warning(1984), Ryland and Ajayi(1984), Brander (1981)and Walmsley-Hart et al.(1999) found similar temdencies in several species of skates and Martin and Cailliet(1988) found comparable results in the bat ray(Myliobatis californica). Holden(1977), Warning(1984), Ryland and Ajayi(1984), Brander (1981)and Walmsley-Hart et al.(1999) found similar temdencies in several species of skates and Martin and Cailliet(1988) found comparable results in the bat ray(Myliobatis californica).

22 .

23 Conclusion

24 Our study provides some basic age and growth parameters for the winter skate and it supports the hypothesis that L. ocellata, like other elasmbranchs, require conservative management because they grow slowly and are susceptible to overexploitation. Our study provides some basic age and growth parameters for the winter skate and it supports the hypothesis that L. ocellata, like other elasmbranchs, require conservative management because they grow slowly and are susceptible to overexploitation.

25 Thanks for your attention

26

27 IAPE

28 Kruskal-Wallis one way analysis

29 K-W one way( 無母數檢定 ): 母體中取得隻隨機樣本大於等於 3 母體中取得隻隨機樣本大於等於 3 不是常態分佈 不是常態分佈 有序位類別 有序位類別 K-W 檢定是提供我們檢定母體是否相同的另一 統計法。

30 IAPE( 平均百分誤差指數 ) N= 總樣本數 N= 總樣本數 R= 樣本重複計算之次數 R= 樣本重複計算之次數 X ij = 第 j 個樣本於第 i 次計數之輪紋數 X ij = 第 j 個樣本於第 i 次計數之輪紋數 X j = 第 j 個樣本重複計數之平均輪紋 X j = 第 j 個樣本重複計數之平均輪紋

31 補充問題

32 Q :反推算? ANSWER : 以體長或椎徑來推估相互值

33 Q :哪兩種檢定可以檢定硬骨魚之體 長椎徑關係? ANSWER : 1. 最大概似法〈 Likelihooh function 〉可檢定 硬骨魚之體長椎徑關係 2. 先以 VBGE 推算雌雄之值再以 ANCOVA 檢定

34 y=a+bx

35 Q : SD 和 SE 之差別? ANSWER : SD (standard deviation) 標準差即母體的標準 差 SE (standard error) 標準誤即母體變異數不知 道的情況之下,或是我們用樣本變異數估計 母體變異數的情況下,稱為 SE Winter skate

36 Raja ocellata 之分類系統表 Raja ocellata 之分類系統表 脊椎動物亞門 Subphylum Vertebrata 軟骨魚綱 Chondrichthyes 板鰓亞綱 Elasmobranchii 鯆魮目 Rajiformes 鯆魮科 Rajidae 鰩屬 Raja 眼斑鰩 Raja ocellata 本魚種非台灣魚種 脊椎動物亞門 Subphylum Vertebrata 軟骨魚綱 Chondrichthyes 板鰓亞綱 Elasmobranchii 鯆魮目 Rajiformes 鯆魮科 Rajidae 鰩屬 Raja 眼斑鰩 Raja ocellata 本魚種非台灣魚種


Download ppt "Age and growth estimates of the winter skate (Leucoraja ocellata) in the western Gulf of Maine 西緬因灣眼斑鰩年齡與成長評估 James A. Sulikowski Michael D. Morin Seung."

Similar presentations


Ads by Google