GROWTH, BIOENERGETICS AND LIFE-SPAN OF OCTOPUS CYANEA AND OCTOPUS MAYA A DISSERTATION SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAII IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN ZOOLOGY AUGUST 1976 By William F. Van Heukelem Dissertation ComInittee: Ernst S. Reese, Chairman Richard E. Young John E. Bardach John Stimson Robert May We certify that we have read this dissertation and that in our opinion it is satisfactory in scope and quality as a dissertation for the degree of Doctor of Philosophy in Zoology. DISSERTATION COMMITTEE Chairman ii ABSTRACT The objectives of the work undertaken were to: (1) rear Octopus cyanea and Octopus maya through all stages of the life cycle in the laboratory; (2) measure growth rates; (3) determine energy budgets; (4) examine the effects of temperature, size and age on food intake, growth, metabo- lism and conversion efficiency; and (5) determine life-spans of the two species. Attempts to rear Q. cyanea through the planktonic stage were unsuccessful and data were obtained on feral animals in the laboratory. o. maya was reared through four generations from eggs collected at Campeche, Mexico. Animals were fed ad libitum on living crabs. Weights were recorded at IS-day intervals and food intake was quan­ tified. Dry matter, ash and caloric content of crab and o. cyanea samples were determined. Animals grew exponentially for the first third of their benthic life, doubling their weight every 11-13 days at 220 - 27 0 C. The exponential growth phase was followed by a per­ iod of logarithmic growth which terminated at full sexual maturity. Average maximum sizes attained by the two species were comparable (3.2 kg for Q. ~aya and 3.6 kg for Q. cyanea). o. cyanea settles from the plankton at an esti­ mated weight of 0.3 g and attains maximum size about 10.5 months later. o. maya hatched as benthic juveniles weighing iii 0.1 g and grew to maximum size in about 8.5 months. Maximum size attained by both species varied from several hundred grams to several kilograms depending on food availability. Assimilation efficiency of o. cyanea was very high (95%) and independent of animal size and food ration size. Gross growth efficiency of both species averaged about 40% on a wet weight basis and was independent of size (old animals excluded) and temperature. The relationship between food intake and growth was linear in both species and showed no sign of decrease at high ration level. Material budgets indicated that on a wet weight basis, 40% of ingested food was used in growth, 55% in maintenance and 5% was not absorbed. Energy budgets on a caloric basis indicated that 60% of ingested energy was used in growth, 36% in total metabolism and 4% voided as feces. Rates of food intake, growth and metabolism were about twice as high at 300 as at 200 C. Females of both species died after brooding their eggs and males died at about the same age. o. cyanea had a life­ span of 12-15 months from settlement and Q. maya lived an average of 10 months from hatching in the laboratory. Low light intensity and elevated temperature in the laboratory were thought to produce early spawning and hence short life-spans in laboratory animals. iv A theory is presented to explain large variations in size at spawning and lack of seasonality. Growth, differen- tiation, maturation and spawning are viewed as programmed events in the life cycle. Light, temperature and food de­ termine the rate at which the program runs and hence size and age at spawning. Senescence and death are viewed as events occurring after the program is completed. v TABLE OF CONTENTS Page ABSTRACT .... iii LIST OF TABLES. ix LIST OF ILLUSTRATIONS xi INTRODUCTION .•.•.• 1 ~illTHODS AND MATERIALS . 6 Collection of Animals . 6 Rearing . 7 Octopus cyanea rearing attempts • . 7 Octopus maya rearing. 9 Rearing older animals of both species . 9 Data Collection · · · · · · · · · 10 Branding. · · · · · · · · . · · · 10 Temperature · . · · · · · . · · · 10 Growth. · · · · · · · · · 10 Food intake · . · · · · · · · . · · · 11 Energy budgets. · · · · · . · 11 RESULTS 12 Rearing attempts (Octopus cyanea) 12 Rearing Octopus maya .. 15 Growth and Life-span ... 18 Introduction. • . 18 Growth of Octopus cyanea .. 21 Reproduction and Life-span of Octopus cyanea. 29 vi TABLE OF CONTENTS (Continued) Page Growth of free, branded Octopus cyanea . 36 Catch data (Octopus cyanea) .. 38 Food habits (Octopus cyanea) 41 Growth of Octopus maya . 43 Life history of Octopus maya . 54 Catch data (Octopus maya) ... 58 Food habits (Octopus maya) 59 Bioenergetics .. 60 Introduction • 60 Food intake. • . 61 Food intake vs. size . 63 Food intake and growth . 67 Food conversion efficiency 78 Gross growth efficiency vs. ration size. 81 Material and energy budgets - Octopus cyanea 86 Material and energy budgets - Octopus maya 105 Relationships between metabolism, size and energy budgets . • . • . 109 Octopus efficiencies compared with other animals. • . 115 Energy used in reproduction. 123 Temperature, Growth, and Bioenergetics . 120 Octopus cyanea . • . 129 Octopus maya . ..... • 138 vii TABLE OF CONTENTS (Continued) Page DISCUSSION. 156 Growth .. 156 Growth and feeding efficiencies . 162 Aquaculture Potential 168 Cephalopod growth and life-span comparisons . 173 Control of reproduction and life-span in Octopus . • . 182 Programmed Life-spans • . 215 SU~.ffiRY . 203 LITERATURE CITED. 211 , viii LIST OF TABLES Table Page 1. Q. cyanea Age vs. Weight and Growth Rates. 28 2. Growth of Free, Branded O. cyanea .. 37 3. Gut Contents of 2. cyanea. 42 4. Growth of o. maya (Group A) . 45 5. Growth of o. maya Adjusted to 25 o C . 47 6. Comparison of Growth Rates - 2. cyanea and o. may~. • . • . 52 7. Size and Age of o. maya at Various Stages in the Life Cycle-.--.-. 55 8. Food Intake, Growth, Fecal Material, and Shed Sucker Cuticles of Q. cyanea for IS-Day Periods. 89 9. Dry Matter, Ash and Caloric Value of crab and Octopus ........... 92 10. Growth and Assimilation Efficiency of o. cyanea on a Wet Weight, Dry Weight, and Caloric Basis. .. .... 94 11. Energy Budgets of Q. cyanea ....• 97 12. Gross Growth, Assimilation, and Net Growth Efficiency of ,Various Aquatic Animals. 117 13. Growth and Bioenergetics of o. cyanea at four Temperatures. 132 14. QI0 of Growth and Food Intake (0. cyanea). 135 15. 02 Consumption and QIO of 02 Consumption of Q. cyanea at Four Temperatures . .. 137 16. Growth, Food Intake, and Gross Growth Efficiency of 2. maya at 20o C ... 141 17. Growth, Food Intake and Gross Growth Efficiency of o. maya at 30oC ... 142 ix LIST OF TABLES (Continued) Page 18. 02 Consumption of Q. maya at 20° and 300 e 147 19. Factors Affecting Sexual Maturation and Life-span in Octopus .•..... 194 x LIST OF ILLUSTRATIONS Figure Page 1. Growth of Q. cyanea - Double Logarithmic Plot. • . • . 23 2. G=owth of Q. cyanea - Arithmetic Plot 25 3. Growth and Life-span of o. cyanea females 30 4. Growth and Life-span of o. cyanea males 31 5. catch Data - Q. cyanea. 39 6. Growth of o. maya - Double Logarithmic Plot 50 7. Growth of O. maya - Arithmetic Plot . 51 8. Growth Rates of o. maya and o. cyanea compared. 53 9. Food Intake vs. Size - o. cyanea Arithmetic Plot. .. ........ 64 10. Relative Food Intake of O. cyanea and o. maya compared . • .. ... 65 11. Food Intake vs. Growth - o. cyanea. 68 12. Food Intake vs. Growth - O. maya .• 69 13. O. maya - Rates of Food Intake, Growth and Metabolism Compared • • . • . • •• 76 14. Gross Growth Efficiency of O. maya and Q. cyanea • . • • • . • . • • • • • • • 80 15. Gross Growth Efficiency of Octopuses vs. Ration Size . • • . • . • • . •. 83 16. Material Budgets of o. maya at Three Sizes.. 106 o 0 17. Growth of Q. maya at 20 and 30 C . • . 145 o 18. Oxyg8n Consumption of Q. maya at 20 and 30 c. 148 o 0 19. Material Budgets of O. maya at 20 and 30 C. 151 xi LIST OF ILLUSTRATIONS (Continued) Figure Page o 20. Growth Curves of 2. maya at 25 C . 158 21. Relative Growth Rates of Four Species of Octopus Compared . 175 22. Weight vs. Age Curves of Four Species of Octopus. ••.•....•... 178 xii INTRODUCTION This study deals with growth and bioenergetics of two sub-tropical octopuses as whole, individual organisms. It is autecological in nature and does not deal with population, cellular, or biochemical aspects of growth and bioenergetics. Most of the data were obtained in the laboratory, and not in the field. Obj ectives were to: (1) rear octopuses through all stages of their life history; (2) measure growth rates; (3) quantify the relationship between food intake and growth; (4) examine the effects of temperature, size and age on growth and energy budgets; and (5) determine the life~spans of the two species studied. The first species studied was Octopus cyanea (Gray, 1949) . Attempts to rear this species from eggs laid in the labora­ tory were unsuccessful and led to importation and successful rearing of o. maya (Voss and Solis, 1966). Both species are large inshore predators and have some commercial value. Octopus cyanea is found throughout the Indo-Pacific (Robson, 1929) and in Hawaii is commonly known as the "day squid" or "he'e". The commercial fishery is small (about 3,000 kg annually, according to State Fish and Game Records) but sports fishermen probably take three to four times the co~~ercial catch (personal observation). Octopus cyanea is one of the better known octopods. LeSouef and Allen (1933, 1937) recorded egg brooding and 2 hatching of the planktonic young and Dew (1959) described brooding, hatching, and the larvae in somewhat more detail. Van Heukelem (1966) recorded aspects of ecology, feeding, courtship, agonistic and spontaneous behavior of O.