{"created":"2024-04-23T01:55:49.964199+00:00","id":2002511,"links":{},"metadata":{"_buckets":{"deposit":"fe398bc5-ba0d-4423-8ce5-73e3a588193d"},"_deposit":{"created_by":10,"id":"2002511","owners":[10],"pid":{"revision_id":0,"type":"depid","value":"2002511"},"status":"published"},"_oai":{"id":"oai:fra.repo.nii.ac.jp:02002511","sets":["12:14:1716951426151"]},"author_link":["1992"],"control_number":"2002511","item_10002_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"1987-01","bibliographicIssueDateType":"Issued"},"bibliographicNumberOfPages":"105","bibliographicPageEnd":"161","bibliographicPageStart":"57","bibliographicVolumeNumber":"37","bibliographic_titles":[{"bibliographic_title":"日本海区水産研究所研究報告","bibliographic_titleLang":"ja"},{"bibliographic_title":"Bulletin of the Japan Sea Regional Fisheries Research Laboratory","bibliographic_titleLang":"en"}]}]},"item_10002_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"The king crab (Paralithodes camtschaticus), hanasaki king crab (Paralithodes brevipes), horse-hair crab (Erimacrus isenbeckii) and snow crab (Chionoecetes opilio) are the main species of cold sea crabs for which the mass-cultivation of larvae and post-larvae are being studied in Japan. The king crab was one of the most important fisheries in Japan, but the catch of king crab is now decreasing. In 1970 study of crab aquaculture began in Hokkaido, northern Japan. In these studies, environmental effects were examined and there are several potential environmental conditions which may affect survival of crab seedlings. However, there is not enough information concerning environmental effects on the success of mass-cultivation of crab larvae and post-larvae. Thus I carried out an investigation on the effect of environment on growth, survival rate and oxygen consumption from the egg stage to the young crab stage in this study. Life history : Eggs attach to the abdominal pleopods of female crabs where they are brooded for about 300 days at 3˚C until they hatch. There are four planktonic zoeal stages. After approximately 30 days at 8˚C, zoeae moult to glaucothoe that have the ability to swim, but whose morphology is crab-like in appearance. The glaucothoe stage moults to become a young, bottom-dwelling crab that cannot swim. The egg stage is abbreviated as E in this report (for example, the egg stage at 100 days after the fertilization is show as E-100), the zoeal stage as Z, the glaucothoe stage as G and the young crab stage as C. Wet weight increased exponentially with the time (days). The time (days) during one stage was about 30 days until C-2, but this term during one stage from C-3 was about 90 days, and the regression line was bent at C-3. At Z-4, G and C-1, there were large morphological and ecological changes, but the dry weight, wet weight and carapace length at Z-4, G and C-1 was nearly the same. Egg-bearing females cultured at 3 and 8˚C : The effect of water temperature on the survival and development rate at E was studied by cultivating egg-bearing females at 3 and 8˚C respectively in fiberglass flow through (1 liter/min) tanks with a sand filter. The experiment started with four crabs at 3°C and with three crabs at 8℃. Egg clutch volumes at 8℃ decreased rapidly from E-40 and were under 10% at E-70, while egg clutch volumes at 3˚C decreased gradually, and were 10-90 % when the larvae hatched. The yolk volume at 8˚C decreased rapidly from E-120, while the yolk volume at 3°C decreased slowly from E-150. The egg bearing female mated in the laboratory was cultured at 3˚C, and the development stage of these eggs regarded as a standard egg development in order to compare with the developmental stages of eggs between 8˚C and 3˚C. The developmental stages of eggs at 3˚C were the same as the standard. But those at 8˚C were faster than the standard, and there were a lot of fluctuations of the morphological development. The egg development of E-170 at 8°C was the same as that of E-270-E-300 at 3˚C. In order to determine the stage of egg development, measuring the yolk volume is the best method. Survival rate at egg stages : In order to know the effect of water temperature on the development and survival rate of the eggs, eggs removed from the females' pleopods at E-23, E-57, E-166 and E-258 were cultured at -1.8, 3, 8, 13 and 18˚C. Culturing was done in a bacteria-free petri dish with 30 ml sea water for five weeks. At E-23 and E-57, the survival rate at five weeks later was 100% at -1.8, 3 and 8℃, 20-70% at 13˚C, and 20-30% at 18˚C. At E-166, the survival rate at five weeks later was 100% at -1.8, 3, 8 and 13°C and 90% at 18°C. At E-258, the survival rate decreased with the rise in water temperature. Fifty percent of the eggs died at 4 weeks later at 8°C, 3 weeks later at 13˚C and 2 weeks later at 18˚C. The survival rate of eggs at E-250 in the air (100% humidity) was tested at -1, 3, 8 and 13˚C. They survived for over 10 days at -1 and 3˚C, but 50% died at 32 hours later at 18°C. Egg development : Comparisons of the egg development between experimental and standard groups are discussed in the same way as reported previously for long term cultivation of egg-bearing females. The growth rate increased with the rise in water temperature. The size of embryos cultured at higher temperatures at E-23, E-57 and E-166 was smaller than the length of embryos cultured at 3˚C. There might be no morphological change even if the water temperature increased at E-258, and a lot of larvae hatched out with the rise in water temperature. But the survival rate of the larvae was not satisfactory. Hatching rate : The effect of water temperature on the hatching rate of eggs was studied as follow. Eggs were removed from females' pleopods at 4 and 18 days before the larvae would have hatched normally at 3˚C. These eggs were cultured at -1.8, 3, 8, 13 and 18˚C in bacteria-free petri dishes with 30 ml sea water for 6 days, and the hatching rate at each water temperature was observed. In the experiment with eggs of 18 days before the normal hatching, there was no hatch at -1.8 and 3℃ for 6 days, but larvae hatched 4-5 days later at 8˚C, 3 days later at 13˚C and 2 days later at 18˚C. In the experiment with eggs of 6 days before the normal hatching, larvae hatched 3 days later at 8˚C and 1-2 days later at 13 and 18˚C. In order to get an equal growth rate, arise in temperature was an easy method. But the survival rate of post-larvae was low, therefore it was dangerous for eggs to be exposed to warmer temperatures just before hatching. Egg-bearing females cultured from 8 to 3℃ : These data suggest that the temperature from 3 to 8˚C represents an optimum temperature for the developement until the zoea egg stage (about 200 days later from the fertilization at 3˚C), and 3°C represents an optimum temperature from the zoea egg stage. So an egg-bearing female were cultured at 8˚C till E-120 and cultured at 6˚C till the zoea egg stage. From this stage the water temperature was decreased gradually to 3˚C, and the eggs were cultured at 3°C until the larvae hatched. The egg mass volume was 80 % when the larvae hatched and the survival rate at post-larvae was 20-30 %. This survival rate was similar to the survival rates of post-larvae that were hatched from egg-bearing females cultured at 3˚C. This method of controlling the temperature spent less energy than keeping it at 3˚C in summer, and hatching could be advanced by 2 months. Therefore, the same tank could be used two or three times to culture larvae. There is little negative effect of 8˚C warm sea water on eggs until the zoea egg stage (about 200 days later from fertilization at 3℃), and 8˚C water increases growth rates of egg and reduces rearing cost. But from the zoea egg stage, 8˚C affected the survival rate and 3˚C was the optimum water temperature. Survival rate at larval and post-larval stages : The experiment to determine the effect of water temperature on the survival and growth rates was conducted in polyethylene tanks (47× 30× 20 (depth) cm) with 5 liters of sea water at 0, 3, 8, 13 and 18℃. The survival rates at Z and G at 8 and 13°C were higher than those at 3 and 18˚C. The glaucothoe moulted to C-1 at 8 and 13˚C, but all the glaucothoe at 3 and 18˚C died before moulting to C-1. The survival rate from Z-1 to C-1 was 25% at 8°C and 8% at 13˚C. It took 42 days from Z-1 to Z-2 at 0°C, and all the zoeae died before moulting to Z-3. The relationship between the time (days) during each stage and the water temperature applied to the formula log Y=a+b logy X (water temperature is X (˚C) and the time is Y (days)) with a high correlation. The variable b was roughly equal to 1, therefore, these regression formulas were regarded as \"the total integrated temperature\" (XY=C) which was approximately 350˚C days at Z. The zoeae had a large thermal tolerance, but from the viewpoint of growth and survival rate, 8°C was the optimum water temperature. Glaucothoe had the same characteristics. The thermal tolerance at the young crab stage was less than that of the larvae, and the growth rate suggested that an optimum water temperature for cultivation was 8˚C. The thermal tolerance of king crabs is greater than that of hanasaki king crabs, and an optimum temperature is lower than that of snow crab. It seemed that these characteristics might be one reason for the limit of the main distribution of king crabs to more northern parts of Japan than that of snow crabs. Carapace length at young crab stages: The relationship between the water temperature and the growth rate of the young king crabs in some reports gave as the formula log Y=a+bX (the carapace length is Y (mm) and the stage is X) with a high correlation. I replaced these regression formulas with the highest value of b (in other words, with the highest growth rate during each stage). The environmental condition of these results is shown from the highest letter b as follows : more than C-4 at 8-9˚C > less than C-5 at 8-9°C > more than C-4 at 3°C. The growth rate was higher water temperatures and older crabs. Movement and activity at young crab stages : When seedlings were released into the field, they were exposed to the rapid changes of temperature which appeared between the rearing and in the field. Therefore, the effect of water temperature on the movement and activity of young crabs was studied in an experimental tank. Warm sea water (16.5℃) and cold sea water (3℃) was put into each corner of the experimental tank (180×40×10 (depth) cm), and thus created a temperature gradient. Young crab at C-4 or C-5 that were cultured at 3, 8 and 13˚C were released into the tank at 3, 8 and 13˚C. The young crabs that were cultured at 8˚C and released at 13˚C moved the longest distance at 15 minutes after their release. young crabs that were cultured at 13˚C and released at 3°C could not move, as if they were paralyzed. Those that were released at 8 or 13˚C moved actively. They had no tendency to move to the same water temperature where they had been cultured, but they were distributed throughout the locations of the various temperatures. Food consumption at larval and post-larval stages : Experiments to determine the effect of water temperature on the number of brine shrimp nauplii eaten were conducted at -1.8, 3, 8, 13 and 18˚C from Z-1 to C-1. Larvae were put into a petri dish with 100 brine shrimp nauplii with 30 ml of sea water, and the number eaten was counted under a stereoscopic microscope at 24 hours later. The numbers eaten at Z gradually increased with the developmental stage and rising water temperature, but the increase at Z-4 stopped at 8°C. The number eaten decreased sharply at G and C-1. Perhaps brine shrimp are not a good prey for post-larvae. Oxygen consumption : Oxygen consumption at E-20, E-100, E-200 and E-300, Z, G and C-1 was measured at 3, 8 and 13˚C. The specimens were placed in syringes held in a temperature-controlled water bath. In each five syringes were containing 20-100 eggs or a single larva was used. From E-20, E-100 and E-200 oxygen consumption increased, but oxygen consumption at E-200 and E-300 was the same. Oxygen consumption at 13˚C was the highest, the lowest was at 3˚C, and the intermediate at 8°C. Oxygen consumption at Z-1 was about ten times that at E. The oxygen consumption from Z-1 to C-1 at 3˚C was almost the same. The oxygen consumption at Z-3 at 8˚C peaked and then decreased from this stage. Effect of hypoxia on the oxygen consumption : The same method as the experiment of the effect of the water temperature on the oxygen consumption were used to study the effect of hypoxia on the oxygen consumption at 3, 8 and 13˚C. Different levels of oxygen saturation were obtained by passing nitrogen gas through sea water. At 3˚C, the value for oxygen saturation where the oxygen consumption was maintained at a similar rate to oxygen saturation of 90-100 % was the lowest at E-100 and the highest at G. The normal rate of oxygen consumption at lower oxygen saturation suggested that there might be a physiological adjustment for taking up oxygen. At 8 and 13˚C, this physiological adjustment was observed at the lowest oxygen saturation at E-100, the highest at Z-1, and Z-2 and Z-3. A homoeostasis of oxygen consumption at E was observed at an oxygen saturation higher than 50%, and homoeostasis of oxygen consumption at Z, G and C-1 was observed at an oxygen saturation of 70-80% but the gradient at C-1 was above those at Z and G. The effect of water temperature on the oxygen consumption at the hypoxia condition had the same tendency except at G at 3˚C. Effect of salinity on the survival rate : The effects of water temperature and salinity on the survival rate were studied. Eggs that would hatch in about 30 days, Z-1 and Z-2, Z-3 and Z-4, G and C-1 were used in this experiment. Ten eggs or ten larvae were placed in a one-liter beaker and the survival rate after 24 and 48 hours observed. The experimental temperature were at -1.8, 3, 8, 13 and 18˚C and 11 salinity conditions ranging from 0 to 67‰, at intervals of 6.7‰. There were 6 × 11 experiments with pair of observation experiments. The area representing the 100% survival rate at 48 hours later was shown from the largest area as follows: at Z-1 and Z-2 > at Z-3 and Z-4 > at G≒at eggs (about 30 days before the hatch) > at C-1. The tolerance to the change of water temperature and salinity at Z is the highest, and it is the lowest at C. The thermal tolerance in 33.5‰ sea water (approximately the same salinity as natural sea water) was between -1.8 and 18˚C. The eggs, larvae and post-larvae have a large short-term thermal tolerance. Effect of light on the survival rate : The effect of light intensity on the survival rate was conducted in a one-liter beaker with 10 zoeae at 3˚C. The range of light intensity was made by the distance of the artificial light from the beaker. Light intensities were 15,000, 10,000, 5,000 and 2,000 lux at Z-1 - Z-2 and 15,000, 10,000 and 5,000 lux at G and C-1. The survival rate decreased with an increase in light intensity and this relationship was linear for a light intensity above 5,000 lux. The effect of the length of period of light and dark during one day on the survival rate was conducted in a one-liter beaker with 10 zoeae at 8°C. The condition of the light-dark term was as follows : 24L, 16L8D, 8L16D and 24D. The light intensity was 1,000 lux. There was no effect of the light-dark periods on the survival rate. There was no difference of time (days) during each stage. The optimum light intensity is from 0 to 2,000 lux. But when phytoplankton were put in a rearing tank for food, some light intensity was necessary. Therefore the optimum light intensity might be 2,000 lux or more. Rearing in polluted sea water : The larger the number of larvae in the tank, the more polluted the sea water. There might be some effect of polluted sea water on larval survival. Therefore, the effect of the polluted rearing sea water on the survival rate was studied at 8˚C in a one-liter beaker. The range of polluted rearing sea water was created by the transfer of larvae as follows. Eleven beakers were prepared with one liter of sea water (these beakers were numbered as B1, B2, B3, ... B10, B11 and tn B12) and ten zoeae were cultured respectively without B12 (these zoeae group were numbered as A in B1, B in B2, C in B3, ... J in B10 and K in B11). On the next day, A was transferred to B12, B was transfered to B1, I was transfered to B2, ... K was transfered to B10. The sea water in B11 was replaced by fresh sea water. At this next day, A was transfered to B11, ... K was transferred to B9 and the sea water in B10 was replaced by a fresh one. These transfers were continued once a day, and at 11 days later, 11 ranges of polluted sea water were made (A was cultured in the fresh sea water and K was cultured in the polluted sea water and the total number of rearing larvae was 100 zoeae). There was a lot of dust, moulted carapace and leftover food in the tank at 11 days later, but the pH and oxygen saturation were the same as in the fresh water. There was no effect of polluted rearing sea water on the survival rate of larvae. Thus, I studied the effects of more polluted sea water on the survival rate. The volume of sea water in each beaker was 200 ml and the term of the transfer of larvae was once every two days. In this experiment the total number of rearing larvae was 1,000 in a one-liter beaker in the most polluted conditions, but in these conditions there were also no effect of the polluted rearing sea water on the survival rate. Effect of the numbers of larvae and post-larvae : The effect of larval density was studied at the larval stage in 1, 30 and 500-liter tanks and at the post-larval stage in a one-liter tank. At Z in a one-liter beaker, the volume of sea water was 200, 400, 600, 800 and 1,000 ml with 35 zoeae respectively and 200, 400 and 800 ml with 150 zoeae respectively. There was little effect in relation to the volume of water, but there was an effect of density in relation to the number of larvae in one beaker. The optimum numbers of larvae in one vessel (the survival rate was above 80% from Z-1 to G) was less than 10 zoeae in the one-liter beaker, 500 in the 30-liter tank and 20,000 in the 500- liter tank. The larger the rearing tank was, the higher the survival rate of the larvae. At C, there was not a typical effect of the number of young crabs on the survival rate, and the distribution pattern of young crabs on the bottom of the tank during the cultivation was random. The optimum number of young crabs might be under 10 in a one-liter beaker. These results suggest that there may be little effect of density on the survival rate at C, but the main roason of death at C was cannibalism which also occured many times at Z and G. Therefore, protection against cannibalism is one of the most important points to assure success in the mass-cultivation of king crab seedlings. The kinds of food through out this experiment are frozen squid, shrimps and sardines at the adult stage, and brine shrimp nauplii, rotifer and diatom at the larval stage, and cultured brine shrimp and chopped shrimps at the post-larval stage. These kinds of food were satisfactory to culture the larvae and post-larvae, but the cultivation of rotifer needs a warm water temperature (from 20 to 30˚C). The study of optimum food that can be cultured in a cold sea is necessary. Since 1982, the Japan Sea-Farming Association at the Akkeshi branch at Hokkaido has been conducting mass-cultivation of king crab seedlings. The total number at C-1 was 228,400 in 1983 and the survival rate from Z-1 to C-1 exceeded 80% in a 20-ton tank. A method of mass-cultivation of king crab seedlings, exists and an experimental release of king crab seedling into the field is now in preparation. However, there are a lot of unstudied problems in the propagation of king crabs, such as the optimum place, time and management to release and recapture the king crab seedlings.","subitem_description_language":"en","subitem_description_type":"Abstract"},{"subitem_description":"タラバガニ漁獲量は近年著しく減少した.このため種苗放流を含めた増殖的手段を講じようとする研究が,1970年から北海道で始められた.この研究において人工種苗生産技術開発が進められ,タラパガニ人工種苗大量培養技術開発に関して既に多くの報告がなされた.また稚ガニ1期において20万個体規模の種苗生産が可能となった.著者は北海道区水産研究所において多年これらの仕事に携わる中で,卵から親ガニまでの全生活史を通して生残率·成長·酸素消費量·行動など比較的容易に測定あるいは観察できる項目を指標として,これらに影響をおよぼす環境変動を水温その他出来るかぎり多く組合せて,耐え得る環境範囲と最適環境範囲を調べ,最も望ましい飼育条件を示した.1. 成長 腹肢付着卵内の発生段階の判別は,受精から桑実胚期までは細胞数によって可能であり,それ以降は胚の形態により可能であった.しかし,桑実胚期をすぎて細胞の境界が観察出来なくなってから胚盤の出現する頃までは発生段階の判別は出来なかった.また,次のような部位の長さから胚の発生段階の判別が可能であった.すなわち胚の長軸,胚の短軸,胚の高さ,眼柄の長軸,眼柄の短軸,卵の裏側から測定した卵黄の長さ,卵の側面から測定した卵黄の長さである.腹肢付着卵のふ出時期を的確に判断するには,ふ出直前まで変化が容易に観察される卵黄の長さを卵の裏側と側面から測定し,この値の基準値に対する比からふ出時期を推定するのが最も良いと判断された.ゾェア4期·グラウコトェ期および稚ガニ1期の甲長は,ほぼ同じであった.また湿重量および乾重量の増加率は,稚ガニ2期以降の増加率に比べて低かった.水温8℃で飼育した稚ガニ期の成長は,Hiatt の定差図にあてはめるとよく直線に適合した.これはn令期での甲長をX(mm),n+1令期での甲長をY(mm)とすると稚ガニ4期と5期の前後において別々に回帰させたほうが適合性はよくなり稚ガニ4期以下ではY=1.185X+0.991 (r=0.9915)稚ガニ5期以上ではY=1.154X+0.830 (r=0.9452)となる. 湿重量と令期の関係は,令期をX,湿重量をY(mg)とするとY=1.1562 e 0. 8142X (r=0.9952)となる.湿重量と甲長の関係は甲長をX(mm),湿重量をY(mg)とするとY=0.3730X3.5770(r=0.9668)となる.2. 酸素消費量 酸素消費量の対数変換した値は,受精後200日までの卵期では,胚発生が進むにつれて直線的に増加したが,受精後200日と300日の卵の酸素消費量は,ほぼ同じであった.卵の酸素消費量は水温上昇にともない概して増加した.ゾェアの酸素消費量は,卵のそれの約10倍となった.ゾェアの酸素消費量は水温8℃でピークを示した.ゾェア1期から稚ガニ7期までの水温8℃での酸素消費量は,ゾェア1期を1令期,ゾェア2期を2令期, …,グラウコトエ期を5令期,稚ガニ1期を6令期,稚ガニ2期を7令期,…,稚ガニ7期を12令期として,令期をX,酸素消費量をY(μl/h ind.)とすると,次の三つの回帰式であらわすのが最も適合性がよかった.ゾェア1~4期(1令期~4令期) Y=0.3557 e 0.2871X (r=0.8648) グラウコトエ期~稚ガニ2期(5令期~7令期) Y=0.1221 e 0.3179X (r=0.9675) 稚ガニ3期~7期(8令期~12令期) Y=0.05208 e 0.5261 X (r=0.9910) 水温8℃で湿重量8mg以下における稚ガニの酸素消費量は,0.1~0.5(μl/h W.W.(mg))の範囲にあり,ばらつきが大きい.湿重量8mg以上では,湿重量をX(mg),酸素消費量をY(μl/h W.W.(mg))とすると Y=994.23X-0.4612 (r=0.8342) の式で示された.3. 水温 卵期から幼生期における48時間100%生残の水温範囲は,-1.8℃~18℃の約20℃であった.卵期においては30日間50%生残の水温範囲,幼生期においては次の令期に正常な脱皮が観察される水温範囲は次のようになった. 適水温下限は,卵期では-1.8℃,ゾェア1期では0℃,ゾェア2期~稚ガニ1期では3℃であった.適水温上限は,受精後100日前後までの卵期では13℃,受精後200日前後の卵期では18℃,受精後300日前後の卵期では8℃,ゾェア1期~ゾェア3期では18℃,ゾェア4期~稚ガニ1期では13℃となった.長期間にわたる飼育結果等から推定した最適飼育水温の範囲は,受精直後~受精後200日の卵期では3℃~8℃,受精後200~300日の卵期では3℃前後,ゾェア1期~ゾェア3期では3℃~13℃,ゾェア4期~稚ガニ1期では3℃~8℃となった.水温制御のコストおよび飼育効率等をあわせて考えると,腹肢付着卵を持つ親ガニの飼育水温は8℃前後とし,受精後200日よりふ出直前までは3℃,ふ出後は8℃前後で飼育するのが最適と考えられる.ゾェア期における積算温度は水温8℃において最も小さく,約300度日であった.水温8℃で飼育した稚ガニの甲長は,3℃で飼育した稚ガニの甲長に比べて大きかった.水温3℃で飼育していた稚ガニ5~9期では,通常では脱皮を行う時期であるのにこの脱皮をとばして次の脱皮時期まで脱皮が行われない現象が数例観察された.水温3,8,13℃で飼育していた稚ガニ4~5期の幼生を,水温勾配をつけた実験水槽内の水温3,8,13℃を示す部位にそれぞれ移し,行動を観察した.実験までの飼育水温がいずれの場合でも,高い水温を示す部位に移した個体のほうが移動距離は長かった.水温13℃で飼育していた稚ガニを実験水槽の3℃を示す部位に移した時,稚ガニは麻ひ状態になった.今まで飼育されていた水温と異なる水温へ移された稚ガニの移動に方向性はなかった.4. 塩分 塩分と水温を組み合わせた2環境因子実験条件下で48時間100%生残範囲の面積は,ゾェア1·2期 > ゾェア3·4期 > グニウコトエ期 ≒ ふ出30日前の卵 > 稚ガニ1期,の順となり,水温および塩分変化に対してゾェア期の耐性が最も強く,稚ガニ期の耐性が最も弱かった.また,生残率および活発さの度合いから求めた反応曲面の式によると,水温に比べて塩分の影響が大きくなっており,塩分変動のほうが,水温変動に比べて,幼生に与える影響は大きいと思われる. 5. 低酸素 低酸素条件下において,卵期では酸素消費量の恒常性維持の機能が強く,ゾェア期およびグラウコトェ期ではこの機能はほとんど観察されず,稚ガニ期においてはこの機能が若干観察された.6. 照度と明暗の期間 5,000 lux 以上の照度条件下における幼生の生残率は,照度が強いほど,低くなった.照度1,000 luxで1日内の明暗の期間と生残率の問に関連は見られなかった.7. 摂餌量 幼生が摂取するアルテミア·ノーブリウスの個体数(摂餌量)は,水温ー1.8℃および3℃では,ゾェア期を通してほぼ同じであった、水温8℃および13℃では,令期をX,摂餌量をY(摂取されたアルテミア·ノープリウスの個体数/1日)とすると次のような式が得られた.水温8℃では Y=15.360X-3.533 (r=0.7102) 水温13℃では Y=12.902X+5.799 (r =0.7129) 水温18℃では,令期と摂餌量の間に関連は見られなかった.グラウットェ期および稚ガニ期における摂餌量は,ゾェア期における摂餌量の約1/5であった. 8. 飼育密度 水量1 lあたり延べ100~500個体の幼生を飼育した場合,残餌·脱皮殻等が増加しても,幼生の生残率は影響を受けなかった.1 l水槽において幼生を飼育する場合,単位水量あたりの飼育個体数が同じでも,1水槽あたりの飼育個体数が少ない実験例のほうが生残率が高かった.1l水槽,30l水槽および500l水槽における単位水量あたりのゾェアの飼育個体数と生残率の関係は,それぞれの大きさの水槽ごとにほぼ直線に回帰し,これらの直線の傾きはほぼ等しかった.またこれらの直線と生残率を示す縦軸との交点は,500L水槽 > 30L水槽 >1L水槽の順で大きくなった.つまり,単位水量あたりの飼育個体数が同じ場合は,小さな水槽で飼育するより大きな水槽で飼育するほうが生残率は高くなった.生残率におよぼす飼育密度の影響は,脱皮を経ると顕著になった.10×10(cm2)の底面積の角型水槽内における稚ガニの分布様式を,この水槽底面を正方形や円等で仮に枠どりし,これらの区画に入る稚ガニの個体数から検討した.ボアソン分布の理論値に危険率10%で適合しない実験例の全体に占める割合は,枠の取り方により異なり12.7~28%の範囲であった.ボアソン分布の理論値に危険率10%で適合しない実験例の中で一様分布の分布様式を示した実験例は,飼育個体数100以上の実験区において多くなったが,全般的にみると,タラバガニ稚ガニの小型水槽内における分布は,ランダムと考えるほうが妥当性が高かった.","subitem_description_language":"ja","subitem_description_type":"Abstract"}]},"item_10002_publisher_8":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"日本海区水産研究所","subitem_publisher_language":"ja"},{"subitem_publisher":"Japan Sea Regional Fisheries Research 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