Preliminary demographic analysis of the shortfin mako shark isurus oxyrinchus
Download
1 / 33

Preliminary demographic analysis of the shortfin mako shark, Isurus oxyrinchus - PowerPoint PPT Presentation


  • 101 Views
  • Uploaded on

Preliminary demographic analysis of the shortfin mako shark, Isurus oxyrinchus. Mollet H. F. and Cailliet G. M. Contrasting VBGF and Reproductive Parameters for the Shortfin Mako Pratt and Casey 1983 vs. Cailliet et al. 1983.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Preliminary demographic analysis of the shortfin mako shark, Isurus oxyrinchus' - king


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Preliminary demographic analysis of the shortfin mako shark isurus oxyrinchus

Preliminary demographic analysis of the shortfin mako shark, Isurusoxyrinchus

Mollet H. F. and Cailliet G. M.


Contrasting VBGF and Reproductive Parameters for the Shortfin MakoPratt and Casey 1983 vs. Cailliet et al. 1983


Age at Maturity of Female Shortfin Mako Shortfin Mako(when 10 and 90% are mature)1. L (t) = 3.73 - (3.73 - 0.70) e(-0.203 t), Pratt and Casey 19832. L (t) = 3.21 - (3.21 - 0.76) e(-0.072 t), Cailliet et al. 1983


Observed and Calculated (from VBGF) Growth Rates Shortfin Makofor the Shortfin Mako1. L (t) = 3.73 - (3.73 - 0.70) e (-0.203 t), Pratt and Casey 19832. L (t) = 3.21 - (3.21 - 0.76) e (-0.072 t), Cailliet et al. 1983


Band count and capture date frequency histograms
Band-Count and Capture-Date Shortfin MakoFrequency Histograms


Check on seasonality of bands based on preliminary band count data sheets
Check on Seasonality of #Bands Shortfin Mako(based on preliminary band count data sheets)


Growth rates of southern california makos from modes of length frequency histograms
Growth Rates of Southern California Makos from Modes of Length-Frequency Histograms

  • ~50 cm/yr at age 0.25 yr~34 cm/yr at age 1 yrFall data Cailliet et al. 1983 assuming 2 bands/year.

  • ~45 cm/yr at age 0.67 yr~30 cm/yr at age 1.67 yrO'Brian and Sunada 1994, modes at AL = 42 and 53 cm (TL = 122 and 152 cm) from 2+ and 3+ year old makos, respectively.

  • ~60 cm/yr at age 0.25 yr~30 cm/yr at age 1.0 yr20-25 cm/yr at age 2.0 yrHanan et al. 1993, modes at AL = 34, 44, and 54 cm (TL = 100, 130, and 150-150 cm) from 0.5, 1.5 and 2.5 year old makos, respectively.


D09 to be completed if needed
D09 To be completed if needed Length-Frequency Histograms

  • 2 bands per year (Atlantic) vs. 1 band year (Pacific)?

  • No reliable data until 1994

  • Parker, H. W. and F. C. Stott 1965. Age ,size, and vertebral calcification in the basking shark Cetorhinus maximus (Gunnerus). Zoologische Mededelingen (Leiden) 40, 305-319. Received 1/21/97

  • Comparison of age/length relationship with length/rings relationship suggested 2 rings (=bands?) per year and a gestation time of 3.5 years (7 rings (=bands? at birth

  • Was questionend by Pauly 1978 (not seen by me)

  • Holt and Bedford 1993. Used 3 makos with TL = 1. 7 and 1.8 m in tagging study and used Pratt and Casey 1983 to estimate age of 2-year old juveniles.

  • Branstetter and Musick 1994. 2 Bands/year for the sandtiger


D10 needs work if needed
D10 Needs work if needed. Length-Frequency Histograms


Catch curves estimation of survival from age composition ricker 1977 krebs 1989
Catch Curves Length-Frequency HistogramsEstimation of Survival from Age Composition(Ricker 1977, Krebs 1989)

  • Right limb is a survivorship curve that is both age-specific and time-specific if the following assumptions are met:

    • Survival rate is uniform with age

    • Survival rate is uniform with time

    • Sample taken randomly from age groups involved

    • Recruitment is constant for all age groups

  • If these 4 assumptions are violated, the right limb of the catch curve will often not be a straight line.


  • Catch curve of female shortfin makos
    Catch Curve of Female Shortfin Makos Length-Frequency Histograms


    Catch Curve for Exp. Drift Longline Fishery Length-Frequency Histogramsin Southern California during 1988-1991O'Brian and Sunada 1994


    Catch Curve for Makos taken by Japanese Longliners off the eastern coast of Australia(Stevens 1992)can add n=98 females, Z = 0.61 but # to small to derive meaningful catch curve. Could try smoothing.


    Catch Curve for Shortfin Mako off East Northland and Bay of Plenty, New Zealand 1974-90 (Saul and Holdsworth 1992)(females extracted and large females from off-shore added)


    Catch Curve for Female Shortfin Mako from western North Atlantic, n = 1113 (Casey and Kohler 1992)Z= 0.70, too large! but why,



    D? Mejuto for years 1983 and 1984 1961-90 (Pepperell 1992)combinend female data for the 2 years then calculatet age_FL. Was done later!


    Summary of z s from catch curve for female shortfin makos
    Summary of Z's from Catch Curve 1961-90 (Pepperell 1992)for Female Shortfin Makos


    Parameters for demographic analysis
    Parameters for Demographic Analysis 1961-90 (Pepperell 1992)

    • 1. Length at Age (VBGF).

    • 2. Estimate of natural mortality (M) Hoenig 1983 (requires max. age estimate, we used 7 ln2/k = 23.9 years (k = 0.203 year-1).Pauly 1974 (requires max. size = 3.73 m TL, VBGF k = 0.203 year-1, and water temperature T = 20 C.

    • 3. Estimate of fishing mortality (F) or total mortality (Z = M + F); we used catch-curve derived Z.

    • 4. Natality, to be discussed next.


    Effective Natality vs. TL 1961-90 (Pepperell 1992)10, 50, 90% mature at TL = 2.60, 2.72, 2.85 m)mx(TL) = (1/4) 0.572 TL2.66e(-47.481+17.505 TL)/(1+e(-47.481+17.505 TL));


    Effective Natality vs. Age 1961-90 (Pepperell 1992)10, 50, 90% mature at age 4.8, 5.4, 6.1yrmx = (1/4) 0.572 TL2.66.e(-47.481+17.505 TL)/(1+e(-47.481+17.505 TL));with TL = 3.734-(3.734-0.702)e(-0.203 age)


    Life-History Table of 1961-90 (Pepperell 1992)Isurus oxyrinchusInput: VBGF, Z = 0.30 year-1, mx = effective natalityOutput: Ro = 2.0, G = 9.0 year, r = 0.076 year-1, er = 1.08


    Life-History Table of 1961-90 (Pepperell 1992)Isurus oxyrinchusInput: VBGF, Z = 0.34 year-1, mx = effective natalityOutput: Ro = 1.08, G = 9.72 year, r = 0.0084 year-1, er = 1.01


    D23 To be finalized if needed. Got a slight problem because Z derived from the corresponding catch curve is expected to be 0.34 (input) and not 0.348


    Life history parameters for isurus oxyrinchus f starts at age 0
    Life History Parameters for Z derived from the corresponding catch curve is expected to be 0.34 (input) and not 0.348Isurus oxyrinchus (F starts at age 0)


    Life history parameters for isurus oxyrinchus first year mortality 2x subsequent mortalities
    Life History Parameters for Z derived from the corresponding catch curve is expected to be 0.34 (input) and not 0.348Isurus oxyrinchusFirst year mortality 2x subsequent mortalities


    Life History Parameters for Z derived from the corresponding catch curve is expected to be 0.34 (input) and not 0.348Isurus oxyrinchususing 3-Year Reproductive Cycle (F= 0.05 and 0.10 year-1start at age 0)


    Life history parameters for isurus oxyrinchus f 0 05 and 0 10 year 1 start at age 0
    Life History Parameters for Z derived from the corresponding catch curve is expected to be 0.34 (input) and not 0.348Isurus oxyrinchus (F= 0.05 and 0.10 year-1start at age 0)


    Life history parameters for isurus oxyrinchus m 1 2 x m 1 j
    Life History Parameters Z derived from the corresponding catch curve is expected to be 0.34 (input) and not 0.348for Isurus oxyrinchusM1 = 2 x M1+j


    Life history parameters for isurus oxyrinchus f 0 05 and 0 10 year 1 start at age 01
    Life History Parameters for Z derived from the corresponding catch curve is expected to be 0.34 (input) and not 0.348Isurus oxyrinchus (F= 0.05 and 0.10 year-1start at age 0)


    Life history parameters for sharks adding to cort s 1995 and 1996
    Life History Parameters for Sharks Z derived from the corresponding catch curve is expected to be 0.34 (input) and not 0.348(Adding to Cortés 1995 and 1996)


    Finite Rate of Population Change (e Z derived from the corresponding catch curve is expected to be 0.34 (input) and not 0.348r) vs. Z(Southern Hemisphere vs. Western North Atlantic Age at Maturity)


    Finite Population Rate Decrease (e Z derived from the corresponding catch curve is expected to be 0.34 (input) and not 0.348r) vs. ZBase calculation with observed fecundity and southern hemisphere age at maturity


    ad