# Fish Stock Data - Excel

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```					                              Data for Stratified Sampling Problem
The data are the basket weights and numbers of fish sampled.
Stratum                             Big Fish      Med. Fish     Small Fish
Total No. Baskets                           31            47             28
No. Baskets Sampled                          10            10             10
Weight No.Fish Weight No.Fish Weight No.Fish
The Sample Data                    77.3        9  82.8      19   39.3      35
125.6       14  29.9      17   86.5      40
114.4       13  31.2      19  181.9      44
162.2       18  73.8      15   59.6      31
65.1        8  86.8      20   86.6      44
41.9        5 266.4      24   31.0      25
154.1       20  93.8      23   96.3      42
104.9       13  67.6      21   60.6      39
79.7       10 129.1      18   88.8      34
91.0       13 256.6      21  101.5      27
(1) Estimate the average weight of a basket of fish.
(2) Estimate the total weight of all the baskets of fish.
(3) Estimate the average weight of a fish.
(4) Estimate the total number of fish in the market.
(5) Suggest a better way to sample for the average basket weight.

c5616182-1550-43bf-aa16-3b6d79233a7c.xls          Stratified Sampling                4/19/2011
You are preparing to do a stock assessment and have collected samples of fish
from the two major ports that exploit a certain fish stock. Some of the data
available to you are sample tallies by port of the number of immature and mature
fish by size class (below).

(a)    Using a least-squares approach, fit logistic curves to each of the two

Prop_Mature( Len ) = 1 / { 1+ exp[ -B * ( Len - L50 ) ] }

(b)    Repeat (a) but this time using a weighted least-squares approach. The
weights for each (Prop_Mature,Len) data pair should be inversely
proportional to the variance of the Prop_Mature.

(c)    For the stock assessment you need a single maturity versus length
curve. Discuss how you might derive this curve from the information
available to you. Discuss what additional information you might be able
to acquire and how you would use it for deriving a "combined" curve.

North Port               South Port
Length        N Mature        N Immat. N Mature N Immat.
10                                       0       20
12                                       1       19
14                                       1       19
16                                       1       19
18                                       4       16
20                                       2       18
22              4              16        6       14
24              3              17        9       11
26              11              9       10       10
28              9              11       13        7
30              9              11
32              18              2
34              17              3
36              18              2
38              17              3
40              20              0

Length-Maturity Relationship
c5616182-1550-43bf-aa16-3b6d79233a7c.xls                                     4/19/2011
s of fish

d mature

ch. The

be able

Length-Maturity Relationship
c5616182-1550-43bf-aa16-3b6d79233a7c.xls                           4/19/2011

```
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Description: Fish Stock Data document sample