THE A€L”IFICJIAL PROPAGATION OF MARINE FIBH
7
sea-fish culture was accompanied by the following term official statement : “ Hatchery production of marine commercial-fish species was
terminated in 1962 since research had failed to disclose that worthwhile
benefits were obtained from such stocking ” (Duncan and Meehean,
1984). In 1960, the sole surviving British hatohery at Port Erin,
Isle of Man, switched from larval production to researoh into marine
$&-rearing techniques.
111. MARINE FISH HATCHERY TECHNIQUES
Although the American marine hatchery programme started in
1878, it remained on an experimental scale until Woods Hole hatchery
was built in 1886. The previous year, Capt. Dannevig had begun
commercial cod hatching at Fladevigen ; in two respects the Norwegian
technique for obtaining and hatching eggs differed from that practised
in America. Firstly, Dannevig (1910a) relied on the uninhibited spawning of cod in large marine ponds for his egg supply, as opposed to the
American “ stripping ” technique. Secondly, he invented a rocking
incubator for pelagio fish eggs, permitting a greatly inoreased output
of fry per unit of incubator apace. Other European sea-fish hatcheries
adopted Norwegian techniques. In 1906, Woods Hole dropped the
artificial fertilization technique in favour of pond-spawning, though
spawn-takers continued to operate aboard commercial fishing vessels
to supply the hatcheries at Gloucester and Boothbay Harbor.
A. American method8
1. Spawn-taking aboard fishing vessels
A full account of egg collection and incubation techniques was
edited by Brice (18981, in “ A Manual of Fish-Culture ”, published as
an appendix to the U.S. Fish Commission’s report for 1897. Spawntakers equipped with bucket, dipper, siphon, thermometer and tin
spawn-kettle were put aboard oommercial fishing vessels during the
cod spawning season (Nov.-April) off the New England coast. Ripe
fish were selected f;om the catch, and the eggs of the female stripped
into a moistened bucket. Sufticient milt w&s added to fertilize the eggs,
the whole gently mixed and left for 10-20 min. &a weter was then
added, with frequent renewals to remove all slime and excess milt.
Floating eggs were transferred to clean sea water in the spawn-kettle ;
dead and “ green ” (unripe) eggs were thrown away. This technique,
the so-called “ dry ” method of artificial fertilization, was found by
experiment to yield 8 higher percentage of fertilized eggs than the
wet ” method, in whioh the ripe eggs were “ stripped ” into ma water
7
sea-fish culture was accompanied by the following term official statement : “ Hatchery production of marine commercial-fish species was
terminated in 1962 since research had failed to disclose that worthwhile
benefits were obtained from such stocking ” (Duncan and Meehean,
1984). In 1960, the sole surviving British hatohery at Port Erin,
Isle of Man, switched from larval production to researoh into marine
$&-rearing techniques.
111. MARINE FISH HATCHERY TECHNIQUES
Although the American marine hatchery programme started in
1878, it remained on an experimental scale until Woods Hole hatchery
was built in 1886. The previous year, Capt. Dannevig had begun
commercial cod hatching at Fladevigen ; in two respects the Norwegian
technique for obtaining and hatching eggs differed from that practised
in America. Firstly, Dannevig (1910a) relied on the uninhibited spawning of cod in large marine ponds for his egg supply, as opposed to the
American “ stripping ” technique. Secondly, he invented a rocking
incubator for pelagio fish eggs, permitting a greatly inoreased output
of fry per unit of incubator apace. Other European sea-fish hatcheries
adopted Norwegian techniques. In 1906, Woods Hole dropped the
artificial fertilization technique in favour of pond-spawning, though
spawn-takers continued to operate aboard commercial fishing vessels
to supply the hatcheries at Gloucester and Boothbay Harbor.
A. American method8
1. Spawn-taking aboard fishing vessels
A full account of egg collection and incubation techniques was
edited by Brice (18981, in “ A Manual of Fish-Culture ”, published as
an appendix to the U.S. Fish Commission’s report for 1897. Spawntakers equipped with bucket, dipper, siphon, thermometer and tin
spawn-kettle were put aboard oommercial fishing vessels during the
cod spawning season (Nov.-April) off the New England coast. Ripe
fish were selected f;om the catch, and the eggs of the female stripped
into a moistened bucket. Sufticient milt w&s added to fertilize the eggs,
the whole gently mixed and left for 10-20 min. &a weter was then
added, with frequent renewals to remove all slime and excess milt.
Floating eggs were transferred to clean sea water in the spawn-kettle ;
dead and “ green ” (unripe) eggs were thrown away. This technique,
the so-called “ dry ” method of artificial fertilization, was found by
experiment to yield 8 higher percentage of fertilized eggs than the
wet ” method, in whioh the ripe eggs were “ stripped ” into ma water