Small fish protocol in the purse seine herring fishery in NAFO Division 4T

For vessels using a purse seine while fishing herring in NAFO Division 4T

  1. By-catch percentage is defined as the weight of a by-catch species divided by the total weight of the directed species (herring).  The maximum authorized by-catch percentage of mackerel and capelin is set at 10% each of the directed species.
  2. The maximum amount of herring under 23.5 cm allowed in landings is set at 50%.  Monitoring of herring length distribution for the small fish protocol will be conducted by the dockside monitoring company (Annex 2).
  3. The protocol reduces the purse seiner quota based on the percentage of landings that is made up of more than 10% of small fish.  Herring size distribution is determined from samples collected by an independent observer at dockside.  A percentage higher than 10% of small fish in the landed catch results in the large purse seine quota being reduced according to a calculated conversion factor (Annexes 1 and 2). The fishery will stop once the allocation is reached (including adjustment of quota under the small fish protocol) .

Annex 1 – Dockside observers

Sampling protocol for herring length (Small fish protocol)

Sampling frequency:

Sampling must be done for every boat that hailed from sea to a dockside monitoring company.

Field equipment (each dockside observer)

  • Measuring board
  • Sampling sheets
  • Pencil
  • Clipboard

The information to be taken is as follows:
(see the sampling sheet)

Logbook #: Indicate the fishing trip logbook number.

Date: Indicate the date when the sample was taken (day, month, year).

Port: Indicate the port where the fish have been landed.

Sampled by: Sampler name.

Fishing sub-area: Indicate the NAFO sub- area. (see chart)

Vessel name: Indicate the name of the boat sampled.

VRN: Vessel registration number.

Gear: Indicate the type of gear used.

Sampled species: Indicate the name of the species sampled.

Forwarding of data: As soon as completed and verified by the port verification company, the collected data has to be sent to:
David Giard
Resource Management
Gulf Region
E-mail: david.giard@dfo-mpo.gc.ca
Telephone: (506) 851-6494

Fork length measurements

The type of length measurement requested by DFO for the herring small fish protocol is the fork length. The fork length is the distance in a straight line from the tip of the nose to the fork of the tail as illustrated below.

Image of fork length of a herring
Figure 1: Fork length measurements

All herring sampled have to be measured and recorded in different length groupings. A length group is a range of measurement intended to be representative of growth rate patterns and is used to calculate the percentage of undersize herring in the total catch on board the seiner.

The length group that a particular herring is in depends on its size maturity.   Length data is recorded on a data sheet that organizes the information into groups or strata.  Each herring that is measured has its individual length recorded as a tally in the appropriate stratum.  The result is information organized based on the frequency occurrence in the population that the sample was taken from.  This is known as a length frequency distribution.  All length frequency distributions for a given time period from a specific population can be combined to show a very accurate picture of that population.

Sampling method

The dockside observers will have to conduct one type of sampling:

  • Each dockside observer will take a minimum of 4 samples of 50 herrings when 1 to 4 holes are containing herring. When 5 holes are containing herring we require 5 samples of 50 herrings. When 6 holes are containing herring we require 6 samples of 50 herrings.
  • Sample collection must be done:
    • at regular intervals during the whole landing process from the discharge of the dewatering box or;
    • in each individual hold prior to unloading operation.  A minimum of 1 sample per hole must be taken.
  • The herring must be measured at the first decimal precision and rounded to the highest 0.5 cm. (Ex. 24.2 cm measured; 24.5 cm written on the sample sheet, 24.4 cm measured; 24.5 cm written on the sample sheet.)
  • The total number of herring sampled must be indicated on the sampling sheet in each of their size categories.
Image of sampling methods
Figure 2: Sampling method

Sampling tools

Dockside observers will need a measuring board to find the length of the herring.  A measuring board consists of a ruler embedded in a board and a headpiece.  The snout of a fish is placed up against the headpiece and the length is read from the ruler. The observer simply has to round off that reading on the ruler to the highest 0.5 cm. (Ex. A reading of 24.2 cm would be 24.5 cm and a reading of 24.7 would be 25 cm.

Annex 2 – Small fish protocol conversion table

A higher than 10% percentage of small fish (under 23.5 cm) in the catch (landed or discarded) will result in the remaining quota being reduced according to a calculated conversion factor. See the complete conversion table below:

Conversion table to adjust herring catches with more than 10% small herring.
% small herring Conversion factor % small herring Conversion factor
11 1,14 56 5,82
12 1,25 57 5,92
13 1,35 58 6,03
14 1,45 59 6,13
15 1,56 60 6,23
16 1,66 61 6,34
17 1,77 62 6,44
18 1,87 63 6,55
19 1,97 64 6,65
20 2,08 65 6,75
21 2,18 66 6,86
22 2,29 67 6,96
23 2,39 68 7,07
24 2,49 69 7,17
25 2,60 70 7,27
26 2,70 71 7,38
27 2,81 72 7,48
28 2,91 73 7,58
29 3,01 74 7,69
30 3,12 75 7,79
31 3,22 76 7,90
32 3,32 77 8,00
33 3,43 78 8,10
34 3,53 79 8,21
35 3,64 80 8,31
36 3,74 81 8,42
37 3,84 82 8,52
38 3,95 83 8,62
39 4,05 84 8,73
40 4,16 85 8,83
41 4,26 86 8,94
42 4,36 87 9,04
43 4,47 88 9,14
44 4,57 89 9,25
45 4,68 90 9,35
46 4,78 91 9,46
47 4,88 92 9,56
48 4,99 93 9,66
49 5,09 94 9,77
50 5,20 95 9,87
51 5,30 96 9,97
52 5,40 97 10,08
53 5,51 98 10,18
54 5,61 99 10,29
55 5,71    
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