Progress Report on the Killing Method of Whales in the JARPN II coastal
operation.
Hajime Ishikawa D.V.M.
JAPANThe Second phase of the Japanese Whale Research Programs in the Northwestern Pacific Ocean(JARPNII) has been conducted since the 2000 season. This program includes new research target
species of Bryde’s whales, Sperm whales and sei whales (since 2002) adding to common minke
whales. Since 2002 season, coastal operation of the JARPNII started and four Japanese coastal small
type catcher boats took part in minke whaling for the first time in 16 years. Although they haveexperienced commercial hunting of Baird’s beaked whales Berardius bairdii and some pilot whales, it
became necessary to research and improve killing method of minke whales in coastal operation.
DATA COLLECTION, ANALYSIS and TRAINING of GUNNERS
The method of data collection and analysis in the coastal operation followed those for offshore
operation* as same as possible. A researcher on board collected the catch record including TTD for all
whales taken. Necropsy of whale carcass was conducted by a researcher besides the biologicalresearch at the land base of the coastal operation. All data was accumulated and analyzed so as toimprove killing method of whales. Gunners and crews of sampling vessels were briefed at a pre-cruise
meeting on the analysis of the past research for the killing methods and were encouraged to achieve
the shorter TTD and higher IDR.
* see “Progress Report on the Killing Method of Whales in the Second Phase of Japanese Whale Research Program in
the Antarctic Sea (JARPAII) and Northwestern Pacific Ocean (JARPNII)”.

IMPROVEMENT OF GRENADES FOR COASTAL WHALING VESSELSAt the beginning, the Japanese coastal catcher boats equipped 50 mm whaling cannon and small sized
grenades (7g penthrite). However, analysis of data of the first two seasons revealed that the small
penthrite grenades were insufficient to kill minke whales even if their body size was relatively smaller
than offshore whales. Improvement of the grenade for small type whaling catcher boats was conductedfrom 2004 to 2006. Newly developed grenades consist of 27g penthrite with refined fuse and short
type steel head similar to the figure deployed for large sized grenades*.

Results of the JARPN II (coastal operation)
The JARPNII coastal operations were conducted in Sanriku region (Miyagi pref.) in spring andKushiro region (Hokkaido) in summer since 2002 season. Sample size of common minke whales was
50 in the first two years and 120 (total of two regional surveys) from 2004 season. Table 1 shows theTTD and the IDR information for common minke whales from the 2002 to 2009 seasons. Regression
analysis revealed significant decrease of the TTD (p<0.0001) and increase of the IDR (p=0.001)
during research years (Fig. 1).

Table1. TTD and IDR for common minke whales taken in the JARPNII coastal operation. Yearly
total number from 2004 to 2008 season was combined with two surveys (in Sanriku andKushiro region).

Season20022003
2004
2005
2006
2007
2008
2009*Species

Total
numberTime to death(TTD)

MED MEAN
S.D.
50
8:50
8:17
6:07
50
7:40
7:51
2:36
60
5:50
6:51
6:50
Commonminke whale
120
5:20
6:13
7:16
(coastal)
95
3:10
6:42
14:23
106
1:45
4:42
6:52
110
2:15
4:57
7:23
60
0:00
2:54
4:02
*Data of 2009 Kusiro region (59 sample) is not analyzed.

Instant
death rate(IDR)
14.0 %
14.0 %
30.5 %
32.5%
43.2%
47.2%
40.9 %
55.0 %

Fig.1. TTD (left) and IDR (right) for common minke whales in each survey of JARPN II coastal
operation. TTD is indicated by a median value (seconds) and IDR is indicated by a percentage.