Survival and Growth of the American Lobster <I>Homarus Americanus</I

BULLETIN OF MARINE SCIENCE, 61(1): 159–163, 1997

SURVIVAL AND GROWTH OF THE AMERICAN LOBSTER HOMARUS AMERICANUS FED FORMULATED FEEDS

Boon Keng Lim, Nobuo Sakurai, Takuro Sugihara and Jiro Kittaka

ABSTRACT There may be an opportunity to culture American lobsters (Homarus americanus) in Japan using warmed seawater from thermal effluent of power generating stations. Growth parameters for culture lobsters were compared between groups fed two artificial diets (feed A and feed B) or a standard rotational diet. The rotational diet consisted of frozen shrimp, lugworm, and pelleted kuruma prawn feed given on alternate days. The principal protein sources for formulated feed A were squid meal, fish meal, salmon roe meal and prawn meal (in the proportions 43:29:14:14), and for formulated feed B the sources were squid meal, fish meal and shrimp meal (in the proportions 35:29:36). Each diet was given to 14 indi- vidually reared juvenile lobsters (13th - 14th stage, wet body weight ca. 10 g), maintained at 18 ± 2° C for 150 d. Survival in all three treatments was high (ca. 80%) and not significantly different. There were no significant differences between lobsters fed feed A or B in molting frequency (mean ± SD: 2.5 ± 0.5 vs. 2.2 ± 0.5); weight gain ration per molt (1.44 ± 0.05 vs. 1.40 ± 0.10); total percent weight gain (150 ± 59% vs. 116 ± 44%); or, feed conversion ratio (2.0 ± 0.6 vs. 3.0 ± 1.1). However, both diets proved inferior to the rotational diet for all of these factors. Lobsters fed the rotational diet had an average of 2.9 ± 0.5 molts, weight gain ration per molt of 1.56 ± 0.06, total percent weight gain of 376 ± 67%, and a feed conversion ratio of 1.4 ± 0.3. Lobsters fed feed B developed a whitish-blue exoskeleton after 4 - 5 wks, probably due to a carotenoid deficiency, so from day 58 onward, feed B was supplemented with carotenoid oil. The original exoskeleton color recovered after three molts. Lobster given feed B also seemed to take longer than those receiving feed A to harden the new exoskeleton after molting. Neither of the formulated feeds is adequate to replace the rotational diet.

Culture of American lobster, Homarus americanus, to marketable size with survival rates greater than 60%, has been experimentally achieved in 3 ys, using warm discharged seawater from a power station (Sakurai et al., 1994). The lobsters in that experiment were fed frozen shrimp (Anisomysis ijimai), live lugworm (Perinereis vancaurica spp. tetradentata), and pelleted kuruma prawn feed (Nippai Co.) in a daily rotation (the “rotational diet”). However, use of live diets for lobster culture is made difficult by serious problems in stor- age and management. In addition, diet residues decompose quickly, and may cause deterio- ration of rearing water quality. Therefore, the current study was conducted to evaluate survival, growth, and feed conversion ratios of lobsters fed two artificially formulated diets in comparison to those fed the rotational diet.

MATERIALS AND METHODS

The two formulated feeds were prepared at the laboratory of Nippon Formula Feed Mfg. Co., Ltd., Tokyo. Table 1 shows the formulations of the two feeds (A and B). Feed A was made with squid, fish, salmonid roe, and prawn meal, while feed B was made with squid, fish, and shrimp meal. Shrimp meal in feed B was derived from the frozen shrimp that was also used in the rotational diet. Carbohy- drates were represented by alpha starch in feed A and by gluten in feed B. Soybean lecithin was added to feed B only. Table 2 shows chemical analyses of the rotational diet and two formulated feeds. The chemical compositions were analyzed at Japan Food Research Laboratories, Tokyo. Crude protein

159 160 BULLETIN OF MARINE SCIENCE, 61(1): 159–163, 1997

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FBAdee Feed I)ngredient()%(% Squidmeal1 208.823. Fishmeal1 129.219. Salmonidroemeal1 9.6 Prawnmeal1 9.6 Shrimpmeal2 24.0 Short-neckedclammeal2 20.02. α–starch 9.6 Gluten 9.6 Yeastmeal3 96.69. Mineralmix4 48.84. Vitaminmix5 29.92. Cholesterolmeal1 10.01. Soylecithin 2.0 Squidoil1 29.91. 1NipponChemicalFeedCo.,Ltd. 2KajimaMarineScienceLab. 3KirinBreweryCo.,Ltd. 4Dipotassiumhydrogenphosphate23.4%,calciumphosphatetribasic31.8%,magnesiumsulfate heptahydrate35.6%,sodiumdihygrogenphosphatedihydrate9.2%. 5PABA0.32%,biotin0.01%,inositol12.62%,nicotinicacid1.26%,capantothenate1.89%, pyridoxineHCl0.37%,riboflavin0.26%,thiamineHCl0.13%,Menadione0.13%,β–carotene 0.3%,α–tocopherol0.63%,cyanocobalamine0.002%,calciferol0.038%,Naascorbate63.09%, folicacid0.02%,cholinechloride18.93%. level of the two formulated feeds was as rich as that of the pelleted kuruma prawn diet. Since the moisture content of lugworm and frozen shrimp was high, other components were comparatively low. Carotenoid oil was added to feed B only, from the 58th day onward. All feeds except lugworm were stored at -20° C. The experiment consisted of three treatments, each using 14 lobsters in the 13th or 14th stage (wet body weight about 10 g). Each treatment group received only one diet, either feed A, feed B, or the rotational diet. The lobsters were reared in individual 300-cm3 compartments set in a FRP rearing tank with flow-through seawater. Sea water was passed through a sand filter, disinfected by ultravio- let irradiation, and adjusted to 18 ± 2° C before entering the rearing tanks, which were always kept dark by a shading sheet. Lobsters were fed and checked each morning for molting and uneaten food that was removed. The feeding ration was 1.4% of wet body weight, and was adjusted after weighing each molt. Since the moisture content of lugworm and frozen shrimp exceeded 80%, the feeding ratio for these two components of the rotational diet was increased to five times that of the formulated feeds. The experiment was conducted for 150 d. Initial and final wet body weights of the lobsters in each treatment were measured to calculated growth rates during the experiment. Weight gain per molt was calculated by measuring wet body weight 5 d after each molt. Survival rate and molting frequency, and feed conversion ratio (dry weight of feed given/wet body weight gain) were also determined. Growth parameters were compared using a t-test, and differences were considered significant at the level of ααα = 0.05. LIM ET AL.: FORMULATED FEEDS FOR AMERICAN LOBSTER 161

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Ftsdeefdetalumro Rotationaldie CAompositionFBeedFaeedPmelletedKurumLnugworFroze Pprawndiet shrim M1oisture(%)80.110. 86.833.82. C9rudeprotien(%) 542.589.537.101.14. C3rudelipid(%) 100.90. 87.19.0. C9ellulose(%) 11.10. 22.06.0. A1sh(%) 186.171.137.27.2. C8alcium(%) 33.21. 34.04.00. C7holesterol(%) 05.18. 01.01.0. P8hospholipid(%) 39.39. 33.04.0. T8otaltocopherol(mg/100g)904.1216.959.16.1. T8otalcarotenoids(mg/100g)1*1.161.8101.18.4. *2%carotenoidoilwasaddedtofeedBfromthe58thdayofrearing.

RESULTS

Table 3 shows initial and final wet body weight, survival, growth parameters, and feed conversion ratio of the lobsters fed each diet. Survival rates were 12/14 for feed A and the rotational diet, and 11/14 for feed B; these are not significantly different. Death of lobsters always occurred after loss of appetite was observed for several days before molting. Lob- sters fed the rotational diet molted about 3 times during 150 d of rearing, and body weight increased an average of 56% per molt. Lobsters given feeds A and B exhibited significantly poorer results. Lobsters fed the rotational diet exhibited a significantly higher total weight gain (mean ± SD: 316 ± 67%) than those given the two formulated feeds (feed A, 150 ± 59% and feed B, 117 ± 44%). The feed conversion ratio for lobsters on the rotational diet (1.4 ± 0.3) was significantly lower than for those given feed A (2.0 ± 0.6) or feed B (3.0 ± 1.1). These results suggest that an equivalent weight gain could be achieved with less feeding of the rotational diet. Exoskeleton color of the lobsters given feed B appeared whitish-blue after 4 - 5 wks. Although 2% carotenoid oil was added to feed B from the 58th day of rearing, the exoskeleton did not return to the original color (dark red) until the end of the experiment.

DISCUSSION

Lobsters given either the two formulated feeds or the rotational diet showed no significant differences in survival. However, both of the formulated feeds were inferior to the rotational diet for all growth parameters (Table 3). The percent composition of all diets used for this experiment was comparatively similar (Table 2). Protein composition of all diets used for this experiment was at an optimal level (30 - 60%), as reported by may researchers (Kanazawa 1994). Boghen et al. (1982), Kean et al. (1985), and Koshio et al. (1990) reported that diets containing rock crab (Cancer irroratus) produced superior survival and growth among juvenile lobsters. Presumably, this may also produce good results for older lobsters as well. Nutritional formulations of HFX CRD 84 and BML 81S (Castell, 162 BULLETIN OF MARINE SCIENCE, 61(1): 159–163, 1997

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VAselbaira FBeedFteedRotationaldie Wetbodyweight(g) I9nitial160.2±3.160.5±3.9.8±3. F4inal215.0±11.251.5±8.43.4±16. S9urvivalrate(%)76868 Survivalnumber(n)111221 M5oltingfrequency2.5±0.a2.2±0.5a2.9±0.5b R5atioofweightgainpermolt1.44±0.0c1.40±0.10c1.56±0.06d G2rowthrate(%)149.8±59.e116.5±44.1e315.9±66.5f F6eedconversionratio2.0±0.g3.0±1.1g1.4±0.3h

1989; Castell et al., 1989), which were acceptable standard reference diets for many spe- cies, will provide a basic guideline for further improvements in formulating artificial diets for lobster culture. D’Abramo et al. (1983) noted that pigmentation of cultured lobsters is dependent upon the presence of dietary carotenoids. Therefore, the whitish-blue exoskeleton color of lobsters given feed B was probably due to insufficient carotenoids, though feed B contained 24% shrimp meal. Astaxanthin of the shrimp meal was probably lost due to oxidative ran- cidity during manufacturing, whereas the frozen shrimp was defrosted, boiled, and dried under the sun before conversion to meal form. Mckay (1987) suggested that an optimal dietary astaxanthin concentration in feed for American lobster should be between 50 and 100 µg (approximately 5 - 10 mg 100 g-1 of animal mass). Recovery of the original exoskeleton color of lobsters given feed B was observed only after three subsequent molts which require more than 1 year after carotenoid addition. Menasveta et al. (1994) reported that addition of astaxanthin and cantaxanthin to prawn diets could enhance the growth rate of Penaeus monodon. The carotenoids are essential nutrients in a wide range of biological functions (Latscha, 1990,1991), such as pigmentation and growth. Therefore, we conclude that the lobsters given feed B, which was tempo- rarily deficient in carotenoids, were in poorer condition than those given feed A (Table 3). We also observed, by hand touching of the new cuticle, that lobsters given feed B required a longer period to harden their new cuticle after molting, compared with those given feed A or the rotational diet. This study was a preliminary attempt to formulate an artificial diet for American lobster culture in our aquaculture studies. Aiken and Waddy (1995) noted that growth rates of lobsters reared on available formulated diets are about 50 - 75% of those in lobsters fed natural foods. Unfortunately, these two feeds (A and B) resulted in only 40 - 50% of the growth rates of lobsters maintained on the rotational diet. The results indicate that improvements are necessary, not only in nutritional composition and manufacturing methods, but also in the cost of feed formulation. Estimated cost of feed A and B is approximately 2000 Japanese yen kg-1. To produce 1 kg of lobster costs about 4000 yen using feed A, and about 6000 yen kg-1 using feed B (calculated using the feed conversion ratios). Feeds A and B, however, are cheaper when compared to a cost of 10,000 yen using the rotational diet be- cause pelleted kuruma prawn costs 1500 yen kg-1, lugworm 4500 yen kg-1 and frozen shrimp LIM ET AL.: FORMULATED FEEDS FOR AMERICAN LOBSTER 163

130 yen kg-1. However, both of these two feeds are still uneconomical for use in commercial culture, since a market price of lobster kg-1 is presently around 3000 yen.

LITERATURE CITED

Aiken, D. E. and S. L. Waddy. 1995. Ch. 8 Aquaculture. Pages 153-175 in Jan Robbert Factor, ed. Biology of the lobster Homarus americanus. Academic Press, New York. 528 p. Boghen, A. D., J. D. Castell and D. E. Conklin. 1982. In search of a reference protein to replace “vitamin-free casein” in lobster nutrition studies. Can. J. Zool. 60:2033-2038. Castell, J. D. 1989. Reference diet for Crustaceans: principles of experimentation. AQUACOP. IFREMER. Actes de Colloq. Int. 9:339-354. ______, J. C.Kean, L. R. D’Abramo, D. E. Conklin. 1989. A standard reference diet for crustacean nutrition research. I. Evaluation of two formulations. J. World Aquacult. Soc. 20: 93-99. D’Abramo, L. R., N. A. Baum, C. E. Bordner and D. E. Conklin. 1983. Carotenoids as a source of pigmentation in juvenile lobsters fed a purified diet. Can. J. Fish. Aquat. Sci. 40:669-704 Kanazawa, A. 1994. Nutrition and food. Pages 483-502 in B. F. Phillips, J. S. Cobb and J. Kittaka, eds. Spiny lobster management. Fishing News Books, Blackwell Scientific Publications, Lon- don. Kean, J., J. D. Castell, L. R. D’Abramo and D. E. Conklin. 1985. A re-evaluation of lecithin and cholesterol requirements of juvenile lobsters (Homarus americanus) using crab protein base diets. Aquacult. 47:143-149. Koshio, S., R. K. O’dor and J. D. Castell. 1990. The effect of different dietary energy levels on growth and survival of eyestalk ablated and intact juvenile lobsters Homarus americanus. J. World Aquacult. Soc. 21:160-169. Latscha, T. 1990. Carotenoids in animal nutrition. Carotenoids-their nature and significance in animal feeds. (ISBN 3-906507-03-3), F. Hoffmann-La Roche Ltd., Animal nutrition and health, Basle, Switzerland. 110 p. ______1991. Carotenoids in aquatic animal nutrition. Proceedings of the ASA Workshop on Shrimp Feeding Processing and Nutrition, September 19-25, 1991. Bangkok and Jakarta. Mckay, C. 1987. The effectiveness of dietary astaxanthin supplement in respect to the pigmentation and growth response in the American lobster Homarus americanus. The Crustacean Nutrition Newsletter 4:5-6. Menasveta, P., J. Choosuwan, I. I. Buhler, W. Schierle and T. Latscha. 1994. Effect of dietary astaxanthin and canthaxanthin on the pigmentation of giant tiger prawn (Penaeus monodon Fabricius). Pages 717-720 in L. M. Chou, A. D. Munro, T. J. Lam, T.W. Chen, L. K. K. Cheong, J. K. Ding, K. K. Hooi, H. W. Khoo, H. W., V. P. E. Phang, K. F. Shim and C. H. Tan, eds. Proceedings of the Third Asian Fisheries Forum. Asian Fisheries Society, Manila. 1133 p. Sakurai,N., K. Hagiwara, T. Sugihara and J. Kittaka. 1994. Experimental culture of the American lobster (Homarus americanus) utilizing warm waster water from a power station in Japan. Pro- ceedings of the Fourth International Workshop on Lobster Biology and Management, 1993. Crustaceana 67:233-238.

DATE ACCEPTED: October 21, 1996.

ADDRESSES: (BKL and NS) Hayama marine science laboratory, Kajima Technical Research Institute, 2415 Issiki, Hayama-cho, Miura-gun, Kanagawa 240-01, Japan. (TS) Global Environment Dept., Energy and Environment R&D Center, Tokyo Electric Power Company, 4-1 Egasaki-sho, Tsurumi-ku, Yokohama 230, Japan. (JK) Research Institute for Marine Biological Science, Research Institutes for Science and Technology, The Science University of Tokyo, 74 Onnemoto, Nemuro, Hokkaido 087-01, Japan