ABSTRACT Reproductive investment generally involves a trade-off between somatic growth and energy allocation for reproduction. Previous studies have inferred that jumbo squid _Dosidicus

gigas_ support growth during maturation through continuous feeding (an “income” source). However, our recent work suggests possible remobilization of soma during maturation (a “capital”

source). We used fatty acids as biochemical indicators to investigate energy acquisition and allocation to reproduction for female _D. gigas_. We compared the fatty acid profiles of the

ovary to those of the mantle muscle (slow turnover rate tissue, representing an energy reserve) and the digestive gland (fast turnover rate organ, reflecting recent consumption). For each

maintained body condition during maturation regardless of increasing investment in reproduction and a decline in feeding intensity. Cumulatively, _D. gigas_ adopt a mixed income-capital

breeding strategy in that energy for reproduction is mainly derived from direct food intake, but there is limited somatic reserve remobilization. SIMILAR CONTENT BEING VIEWED BY OTHERS

SIZE-DEPENDENT RESOURCE ALLOCATION TO REPRODUCTION IN JAPANESE ANCHOVIES (_ENGRAULIS JAPONICUS_) Article Open access 29 April 2025 FASTER JUVENILE GROWTH PROMOTES EARLIER SEX CHANGE IN A

PROTANDROUS HERMAPHRODITE (BARRAMUNDI _LATES CALCARIFER_) Article Open access 26 January 2021 FEMALES INCREASE REPRODUCTIVE INVESTMENT WHEN MATED TO LESS SEXUALLY ATTRACTIVE MALES IN A

SERIALLY MONOGAMOUS FISH Article Open access 16 August 2024 INTRODUCTION Life-history theory predicts that individuals should trade-off energy allocation between reproduction and somatic

growth or even survival to maximize lifetime reproductive success1. Squids are characterized by short lifespan, fast growth and considerable flexibility in reproductive characteristics2,3.

Although reproduction is typically semelparous, some species spawn multiple times and others continuously2, and reproductive behavior relates to how energy is allocated to reproduction

during maturation4,5,6,7. For example, the deep-sea squid _Onykia ingens_ reduces somatic growth by utilizing mantle muscle as an energy source to fuel reproduction, which then results in

ovarian development for a terminal spawning event6. In contrast, the purpleback squid _Sthenoteuthis oualaniensis_ apparently supports reproduction using energy acquired directly from food

intake, leading to multiple spawning events and continuous growth before death4. The former is referred to as a capital breeder, and the latter as an income breeder8. Since how energy is

allocated during life is central to life-history theory1, an optimal trade-off between investment in reproduction and somatic growth has been found to maximize reproductive success, and

ultimately determine population size and stability over time9,10,11. The jumbo squid, _Dosidicus gigas_ is one of the most abundant nektonic squid in the eastern Pacific12, as well as the

target species of major cephalopod fisheries13. It plays an important role in pelagic ecosystems locally14, not only because it preys on a wide spectrum of organisms during ontogenesis, but

also because it is prey for other predators, including marine mammals15,16. Similar to other squid species, _D. gigas_ is short-lived, usually 1–2 years17,18, with a single reproductive

episode and multiple spawning events19,20,21. _D. gigas_ also responds to environmental conditions22,23, which influences how it invests in reproductive development, and hence annual

variation of recruitment biomass24,25. Rocha _et al_.2, Nigmatullin and Markaida19 and Hernández-Muñoz _et al_.20 suggested that energy allocation to reproduction in _D. gigas_ is directly

derived from the intake of food, evidenced by the multiple spawning events, non-stop feeding and somatic growth in adults between egg batches. However, recent work by Han _et al_.26 on body

condition and reproductive investment, involving estimates of the gonadosomatic index and the residuals of a regression of gonad weight on mantle length, suggested that _D. gigas_ may also

use energy reserves to support reproductive growth. Fatty acid analyses have been used widely to infer dietary history and trophic ecology for marine species27,28,29, and to some extent, to

provide information on how energy is acquired and allocated to tissue types30,31. In marine environments, many fatty acids, particularly polyunsaturated fatty acids, can be biosynthesized by

certain phytoplankton and microalgae species32. In contrast, marine animals are subject to biochemical limitations in biosynthesis and modification of fatty acids, and directly assimilate

dietary fatty acids in their basic form without modification33,34,35,36. In cephalopods, the digestive gland is important for digestion and absorption37,38, and has a fast turnover of

dietary fatty acids, reflecting more recent food intake (10–14 days39,40), and is hence considered a good indicator of nutritional status due to the high lipid concentration41. In contrast,

tissues such as the mantle muscle are considered the most important energy reserve, with a slower fatty acid turnover rate, that reflects diet over a longer period of time (~4 weeks or

longer39). Thus, whether gonads are formed using income sources or energy stored in the somatic tissues can be evaluated by comparing fatty acid profiles of these fast and slow turnover

tissues with those of the gonads42. This comparison could also reveal whether individuals change feeding habits with maturation to obtain greater energy for reproduction43. Following Lin _et

al_.42 who used fatty acids as biomarkers to determine the mixed income-capital breeding strategy for the female Argentinean shortfin squid _Illex argentinus_, we used fatty acids to

investigate the breeding strategy of female _D. gigas_ with respect to energy acquisition and allocation. More specifically, we analyzed fatty acids in the digestive gland, the mantle muscle

and the ovary to (a) assess whether _D. gigas_ shifts its diet to acquire more energy with maturation, (b) determine the pathway of energy sources for reproduction, and (c) justify whether

the energy reserve in the somatic tissues are used for reproduction. The results of this work will lead to a better understanding of the breeding strategy of _D. gigas_, and also further

support the use of fatty acids to study energy allocation to reproduction for oceanic squid and other species. RESULTS FATTY ACIDS WITHIN TISSUES Twenty-eight fatty acids were found in

female _D. gigas_, of which 19 had relative mean values greater than 0.5% and in total made up 92–98% of total fatty acids (Table 1). For each tissue, most of the saturated fatty acid (SFA)

content was 16:0 and 18:0, most of the monosaturated fatty acid (MUFA) content 18:1n9c and 20:1, and most of the PUFA content 20:5n3 and 22:6n3 (Table 1). The total fatty acid content was

higher for functionally mature animals in all tissues analysed, with the highest values consistently observed in the digestive gland (Supplementary Tables 1–3). SFA content was significantly

lower and PUFA significantly higher in the ovaries of mature animals (stages IV and V) than in those of immature animals (stages II and III) (SFA _F_ = 5.19, _P_ = 0.008; PUFA _F_ = 9.29,

_P_ = 0.0005; Fig. 1a). The higher PUFA content in the ovary of mature animals is expected given it is essential for egg and larval quality35,44,45. However, no individual fatty acid in the

ovary differed significantly between animals at different maturity stages (Supplementary Tables 1 and 5). There were no significant differences in the proportion of the main fatty acid

classes (SFA, MUFA and PUFA), nor in the relative amount of each fatty acid except 20:5n3, between maturity stages in the mantle muscle (Fig. 1b; Supplementary Tables 2 and 5). Similarly,

the content of SFA and PUFA in the digestive gland was found vary, but not differ significantly, among maturity stages (SFA _F_ = 1.05, _P_ = 0.39; PUFA _χ_2 = 1.81, _P_ = 0.61; Fig. 1c,

Supplementary Table 5), and MUFA content and the relative amount of each fatty acid were also not significantly different among maturity stages (Supplementary Tables 3 and 5). Multivariate

analyses revealed considerable overlap in the overall fatty acids between maturity stages for each tissue (Fig. 2). A small but insignificant difference was detected for overall fatty acids

between the ovaries of the four maturity stages (ANOSIM _R_-value = 0.11, _P_ = 0.07), but no significant differences were found for the mantle muscle (ANOSIM _R_-value = 0.04, _P_ = 0.28)

and the digestive gland (ANOSIM _R_-value = 0.02, _P_ = 0.36). SIMILARITY OF FATTY ACID COMPOSITION BETWEEN TISSUES Paired Tests revealed that 11, 9 and 13 of the comparisons of the relative

amount of each fatty acid between the ovary and the mantle muscle, between the ovary and the digestive gland, and between the mantle muscle and the digestive gland, respectively were

significant for animals at maturity stage II (Supplementary Table 7). These numbers were 9, 7 and 12 for animals at maturity stage III (Supplementary Table 9), 6, 5 and 4 for animals at

maturity stage IV (Supplementary Table 11), and 5, 4 and 7 for animals at maturity stage V (Supplementary Table 13). Multivariate analyses revealed that the fatty acid profiles for the ovary

overlapped those for the digestive gland (ANOSIM _R_-value = 0.32, _P_ = 0.001), but not those for the mantle muscle (ANOSIM _R_-value = 0.54, _P_ = 0.001), and that changes in the fatty

acid composition for the ovary and the digestive gland showed a similar dispersed distribution pattern compared to a concentrated pattern for the mantle muscle (Fig. 3). There is greater

similarity in fatty acid compositions between the ovary and the digestive gland during physiological maturation (stage III, _R_-value = 0.26, _P_ = 0.012) and for physiologically mature

animals (stage IV, _R_-value = 0.20, _P_ = 0.026). This is also the case for the ovary and the mantle muscle, even though the extent of similarity was consistently less than that between the

ovary and the digestive gland (Table 2). The extent of dissimilarity between the mantle muscle and the digestive gland was less for physiologically mature animals than animals at other

maturity stages (Table 2). BODY CONDITION, GONADOSOMATIC INDEX AND FEEDING INTENSITY There was a significant positive correlation between body weight excluding ovary weight and mantle length

(log(_BW-OvaW_) = −7.18 + 2.43 × log(_ML_); _r_2 = 0.90, _P_ = 7.08e-13). Most functionally mature individuals (stage V) were heavier for a given length (Fig. 4a). Consequently, significant

differences in body condition (represented by the residuals of body weight excluding ovary weight regressed on the mantle length) were found between maturity stages (ANOVA, _F_ = 6.67, _P_ 

= 0.003; Fig. 4b). The gonadosomatic index (GSI) increased significantly following maturation (K-W test, _χ_2 = 19.05, _P_ = 0.0002; II: 0.58 ± 0.17 (range 0.39–0.92); III: 1.12 ± 0.52

(range 0.67–1.81); IV: 2.86 ± 1.69 (range 1.63–5.84); V: 11.31 ± 6.57 (range 4.25–19.00)). There was a weak but significant correlation between GSI and body condition (GSI = 2.43 + 3.54 × 

BC; _r_2 = 0.41, _P_ = 0.0004; Fig. 5a), suggesting that reproductive allocation is higher when animals are heavier than expected given their lengths. In contrast, the digestive gland index

(DGI) was lower following maturation (ANOVA, _F_ = 4.64_, P_ = 0.012; II: 7.28 ± 1.17 (range 5.68–9.16); III: 7.41 ± 3.36 (range 3.25–11.93); IV: 4.72 ± 0.78 (range 3.82–5.68); V: 3.75 ± 

2.00 (range 1.96–6.94)). DGI was also negatively related to body condition (DGI = 6.41–1.29 × BC; _r_2 = 0.21, _P_ = 0.014; Fig. 5b). These observations indicate that individuals reduce

feeding prior to reproduction, but maintain body condition. DISCUSSION Data on fatty acids show that _D. gigas_ preys on similar organisms during ontogeny, given the same pattern of fatty

acid profiles for animals at different maturity stages in all tissues. Energy for reproduction appears to be driven primarily by concurrent food intake, since the changes in fatty acids in

the ovary closely resemble those in the digestive gland. The fatty acid compositions of the ovary and the mantle muscle change similarity with maturation, most notably from the developing to

physiologically mature stages, indicating that energy reserves are also involved in reproduction. Female _D. gigas_ appear to maintain somatic fitness, although the investment in

reproduction increases with maturation along with a major reduction in feeding intensity. As such, female _D. gigas_ adopt a mixed income-capital breeding strategy, which mostly relies on

continual food intake, coupled with the limited use of stored energy during sexual maturation. Of the tissues analysed in female _D. gigas_, the digestive gland has the greatest fatty acid

content regardless of maturity stage (Table 1, Supplementary Tables 1–3). However, the predominant fatty acids in the main fatty acid classes (SFA, MUFA, PUFA) are similar for each tissue,

with 16:0 and 18:0 most prevalent in SFA, 18:1n9c and 20:1 most prevalent in MUFA, and 20:5n3 and 22:6n3 most prevalent in PUFA (Table 1). The most prevalent fatty acids may be the result of

the fatty acid levels of the diet sources given the limited capacity for biosysnthesis of fatty acids33,34,36. On the other hand, these oberservations are in accordance with the findings of

Saito _et al_.46 and Gong _et al_.47, and are also very similar to the results of studies for other squids such as _Loligo vulgaris_48 and _Todarodes filippovae_49. This may imply that

these fatty acids are the common nutrients for squids, presumably owing to their important roles in cell and organelle function31,50,51, as well as energy sources for rapid growth and

development41,52,53. The significantly lower SFA content in the ovaries of mature animals could be due to energy mobilization for reproductive growth53,54. Studies on trophic relationships

have shown that many species, including cephalopods change feeding habits with increasing size or during maturation to maximize energy intake, enhance growth rate and minimize the risk of

predation55,56,57,58,59,60. In the present study, however, the female _D. gigas_ appear to prey on similar prey items before and after maturation because no significant differences were

found in the relative abundance of each fatty acid among maturity stages for the ovary, mantle muscle (except 20:5n3) and digestive gland (Supplementary Table 5). Further evidence is

provided by the clear overlap and similarity of the overall fatty acid profiles between maturity stages for each tissue (Fig. 2). These findings indicate that the female _D. gigas_ may adopt

a foraging strategy that focuses on the amount and not quality of food, which is not unexpected, as squids are well known for their voracious and opportunistic feeding3,12. Although squids

seem to become more active and successful predators as they mature3, their energy expenditure is higher given the need for increased metabolism with maturation for basic maintenance,

predation and reproductive growth61,62. Preying on species that are caught more easily may be a successful tactic to balance energy expenditure during the period of reproduction when energy

requirements are relatively high6,7,26,42. Indeed, studies have showed that squids including _D. gigas_ are opportunitistic predators at all maturity stages12,63,64, presumably related to

their “live for today” lifestyle10. Among the tissues analysed, consistently fewer fatty acids differed significantly between the ovary and the digestive gland than between the ovary and the

mantle muscle for any maturity stage (Supplementary Tables 7, 9, 11 and 13), and this was supported by the multivariate analyses (Fig. 3, Table 2). These lines of evidence indicate that

there is an energy trade-off between gonad development and resource uptake, with the energy sources for reproduction derived primarily from concurrent intake of prey. The similar despersed

distribution pattern of the fatty acid composition for the ovary and the digestive gland revealed by the NMDS analyses (Fig. 3) might indirectly provide futher evidence of energy allocation

to reproduction acquired directly from food intake, as the fatty acids in the digestive gland reflect the corresponding diets within a more recent period of 10–14 days39,40. Furthermore, the

fatty acid composition between the ovary and the digestive gland is more similar for mature animals (particularly those that are physiologically mature) (Table 2), suggesting an increase in

energy allocation to reproduction from food intake, which is consistent with the gonadosomatic index (GSI) being significantly higher for mature animals (K-W test, _χ_2 = 19.05, _P_ = 

0.0002). It is worth noting that the fatty acid composition in the ovary and the digestive gland appears to vary at the individual level, especially for the ovary at the functionally mature

stage (Fig. 3). A possible reason for this is the fact that squids prey on a wide spectrum of prey items12,63,64. Variation in the fatty acids of the ovary at the mature stage may be also

related to the accumulation of essential fatty acids such as long-chain polyunsaturated fatty acids for egg quality35,44,45 and possible remobilization of short-chain saturated fatty acids

for energy use53,54, since the ovary showed a significant increase of PUFA content and decrease of SFA content with maturation (Fig. 1). However, future studies on the specific fatty acid

requirements for gonad development are needed to address these hypotheses. Reproduction generally constitutes a major fraction of the total energy budget of an adult organism1, and gonad

development in many organisms is fuelled by increased food intake as well as mobilization of previously stored reserves65. In the present study, although the fatty acid composition in the

ovary differed from that in the mantle muscle (Fig. 3), the similarity in fatty acid composition between these two tissues increased from the developing to physiologically mature stage

(Table 2). Meanwhile, the significant reduction of the digestive gland index (ANOVA, _F_ = 4.64_, P_ = 0.012), an index of feeding activity38,66, for mature females suggested a possible

reduction in feeding intensity during maturation. It is therefore reasonable to expect that mature female _D. gigas_ remobilize some of their somatic reserve to provide energy for

reproduction. The energy remobilization of somatic reserves for reproduction is limited and probably only occurs as a complementary source during maturation when the development of the

reproductive organs is significant. This is because the dissimilarity (represented by the ANOSIM _R_-value) in the fatty acid composition between the ovary and the mantle muscle is larger

than that between the ovary and the digestive gland (_R_-value, 0.54 _vs_. 0.32). Meanwhile, female _D. gigas_ have better body condition when mature (Fig. 4B), indicating that the adults

have not used up much somatic tissue. Further, the animals with higher reproductive investment appeared to be in good condition (Fig. 5A), although they fed less given the negative

relationship between body condition and the digestive gland index (Fig. 5B). These lines of evidence suggest that female _D. gigas_ maintain somatic fitness even if some energy reserves are

mobilized. Indeed, the fatty acid composition in the mantle muscle more closely resembles that of the digestive gland for mature animals (Table 2), suggesting that the somatic tissues

continue to incorporate nutrients from feeding. This is in stark contrast to species with synchronous ovarian development, such as _O. ingens_ that mobilizes much of its somatic tissues to

support reproduction6. The pattern of limited use of somatic reserve for reproduction may be an evolutionary tactic to adapt to the asynchronous ovarian development of _D. gigas_2,19, as the

maintenance of somatic condition appears to be important for this species to develop the multiple cohorts of oocytes during the protracted spawning period20,21. CONCLUSIONS Female _D.

gigas_ feed on similar prey items during ontogeny, and adopt a mixed income-capital breeding strategy, in which energy for reproduction is mainly derived from direct feeding, coupled with

limited mobilization of somatic energy. The results confirm the recent suggestion by Han _et al_.26 that the energy reserves in the somatic tissues are remobilized to support reproduction

during maturation. The energy trade-off between reproduction and limited use of energy reserve warrants further research to better understand the life-history strategy of _D. gigas_ in terms

of energy acquisition and allocation both within and across taxa. This study could also contribute to the use of fatty acids as biochemical markers to identify the breeding strategy for

oceanic squids as suggested by Lin _et al_.42. METHODS ETHICS STATEMENT Specimens were collected as dead squids from the commercial jigging fisheries landings, during the fishing season from

June to August 2017. The specimens were analyzed in the laboratory using methods that are in line with current Chinese national standards, namely Laboratory Animals - General Requirements

for Animal Experiment (GB/T 35823-2018). As all material sampled in this work was obtained from commercial fishermen and already dead, there was no requirement for ethical approval of

sampling protocols as it did not include live organisms. SAMPLE COLLECTION Samples were collected from the landings from commercial jig fishery in the eastern Pacific (longitude:

84°07′W~102°27′W, latitude: 00°47′S~08°26′S), from June to August 2017. These were immediately frozen at −30 °C for further analyses in the laboratory. A total of 24 females (14 immature and

10 mature) were randomly selected for the following fatty acids analyses after defrosting at room temperature in the laboratory. Each specimen was assigned a maturity stage following the

scheme proposed by Arkhipkin67, Arkhipkin and Laptikhovsky68 and ICES69, with maturity stages: I immature, II developing, III physiologically maturing, IV physiologically mature, V

functionally mature, VI spawning, and VII spent. Specimens were in maturity stages II to V (Table 3). Specimens at maturity stages II and III were categorized as immature, and specimens at

maturity stages IV and V as mature. The following parameters were also recorded for each specimen: mantle length (ML, mm), body weight (BW, g), ovary weight (OvaW, g) and digestive gland

weight (DgW, g) (Table 3). The gonadosomatic index (GSI; ovary weight/body weight × 100) and the digestive gland index (DGI; digestive gland weight/body weight × 100) were also determined

for each specimen38,70. The ventral mantle muscle (~10.0 g), whole gonad and whole digestive gland were collected for each individual, and separately lyophilized to a constant weight in a

freeze-drying system (Christ Alpha 1–4/LDplus). The digestive gland is a site of digestive absorption and intracellular digestion37,38, and deposits recent intake of dietary fatty acids

(10–14 days) without modification36,39,40,71. The mantle muscle is the most important energy reserve organ7,42,72, and reflects dietary information over a time scale of 4 weeks or

longer39.The dried tissues were ground to fine powder individually, and a 0.2 g subsample was used for fatty acid analysis. FATTY ACID ANALYSES Fatty acid methyl esters (FAME) were analyzed

for each tissue sample of each specimen following the “Determination of total fat, saturated fat, and unsaturated fat in foods - Hydrolytic extraction-gas chromatography” protocol73. Lipids

were extracted by using a mixture of chloroform and methanol 2:1 (v/v)74. To esterify the fatty acids, lipids were introduced into a 25 mL vial with 4 mL of 0.5 mol/L KOH-MeOH, which was

incubated at 90 °C for 10 minutes, shaking for 5 seconds every 2 minutes. Then, 4 ml BF3/MeOH was added and the sample incubated at 90 °C for 30 minutes, shaking for 5 seconds every 5 

minutes, followed by the addition of 4 mL n-Hexane for 2 minutes incubation at a similar temperature. Thirdly, 10 mL saturated NaCl was added and shaken gently, followed by introduction into

a 20 mL centrifuge tube for stratification at room temperature. Finally, the upper hexane layer, which contained the FAME, was transferred to a vial, and evaporated under nitrogen current

with 19:0 as an internal standard. Fatty acids were determined using an Agilent 7890B Gas Chromatography (GC) coupled to a 5977 A series Mass Spectrometer Detector (MSD, Agilent

Technologies, Inc. USA), equipped with a fused silica 60 m × 0.25 nm open tubular column (HB-88: 0.20 μm, Agilent Technologies, Inc. USA). The separation was carried out with helium as the

carrier gas, and a thermal gradient programed from 125 °C to 250 °C, with the auxiliary heater at 280 °C. Individual fatty acid peaks were identified by comparing their retention times with

those of chromatographic Sigma standards. Total fatty acids (total FAs) were determined as mg/g, and individual fatty acids were expressed as percentages of total fatty acids (% of total

fatty acids)36. The individual fatty acids were also grouped into saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA). Fatty acids that

accounted for <0.5% were excluded from statistical analyses. STATISTICAL ANALYSIS The results were expressed as means ±standard deviation. The fatty acid data for each tissue were checked

for normality using the one-sample Kolmogorov-Smirnov test75 (Supplementary Tables 4, 6, 8, 10 and 12). Thereafter, one-way analysis of variance (ANOVA) was used to detect significant

differences in the means of the main fatty acid classes (SFA, MUFA, PUFA) and each fatty acid between maturity stages for each tissue75. When normality was rejected, the data were analyzed

using Kruskal-Wallis tests (K-W test)75. Paired _t_-Tests were used to investigate significant differences for each fatty acid within matched pairs of tissues given maturity stage, and

paired Wilcoxon tests were used when normality was rejected75. Non-metric multidimensional scaling (NMDS) and analysis of similarities (ANOSIM) were applied to assess the differences in the

overall fatty acid profiles between immature and mature stages for each tissue, and to determine the differences in the overall fatty acids between the ovary, the mantle muscle and the

digestive gland. These multivariate analyses of fatty acids have the advantage of pattern recognition28,76, and can be used to determine whether energy for reproduction is from energy

reserves (mantle tissue) or consumption of prey (digestive gland)42. The fatty acid data were square root transformed and Euclidean dissimilarity matrices were used in the NMDS and ANOSIM77.

NMDS and ANOSIM analyses were conducted using the vegan package in R78. The relationship between mantle length (ML) and body weight (BW) excluding ovary weight (OvaW) was examined after

log-transformation, and the standardized residuals of the regression used as an index of body condition6,22, where the residuals provide a size-independent measure of the somatic condition

of an individual at the whole animal level5,6. ANOVA was used to detect differences in the means of body condition, GSI and DGI between maturity stages, and these data were analyzed using

Kruskal-Wallis tests when the normality assumption was not satisfied75. To some extent, the GSI can be used as an indicator of reproductive investment5, while the DGI can be used as an

indicator of feeding intensity38. The linear relationships among body condition, GIS and DGI were investigated to assess the interactions between the soma reserve, reproduction and energy

acquisition. Statistical analyses were carried out using SPSS 20.0 and R version 3.5.078. A test was considered significant when _P_ < 0.05. DATA AVAILABILITY The biological measurement

data and biochemical data (fatty acids) that support the findings of this study are available from the Distant Squid Fisheries Sci-Tech Group (SHOU), but restrictions apply to the

availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and

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3.5.0 (R Foundation for Statistical Computing, Vienna, Austria, 2018). Download references ACKNOWLEDGEMENTS This is a contribution of the Distant Squid Fisheries Sci-Tech Group, SHOU. We

thank the staff members of the Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, Shanghai Ocean University for providing assistance at the

laboratory. We are grateful to technician Shaoqin Wang for the fatty acids determination and Sipeng Xuan for collecting the biological data. We also thank the Editor and an anonymous

reviewer for their insightful comments on the manuscript. Funding for this project was provided by the National Natural Science Foundation of China (41876144) and the Natural Science

Foundation of Shanghai (16ZR1415400) to Dongming Lin, and the National Key Research and Development Project of China (2019YFD0901404), National Natural Science Foundation of China (41876141)

and Shanghai Science and Technology Innovation Program (19DZ1207502) to Xinjun Chen. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * College of Marine Sciences, Shanghai Ocean University,

Shanghai, 201306, China Xinjun Chen, Fei Han, Kai Zhu & Dongming Lin * Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, Shanghai, 201306,

China Xinjun Chen & Dongming Lin * National Engineering Research Center for Oceanic Fisheries, Ministry of Science and Technology, Shanghai, 201306, China Xinjun Chen & Dongming Lin

* Key Laboratory of Oceanic Fisheries Exploration, Ministry of Agriculture and Rural Affairs, Shanghai, 201306, China Xinjun Chen & Dongming Lin * Scientific Observing and Experimental

Station of Oceanic Fishery Resources, Ministry of Agriculture and Rural Affairs, Shanghai, 201306, China Xinjun Chen & Dongming Lin * Laboratory for Marine Fisheries Science and Food

Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China Xinjun Chen * School of Aquatic and Fishery Sciences, University of Washington,

Seattle, WA, 98195-5020, USA André E. Punt Authors * Xinjun Chen View author publications You can also search for this author inPubMed Google Scholar * Fei Han View author publications You

can also search for this author inPubMed Google Scholar * Kai Zhu View author publications You can also search for this author inPubMed Google Scholar * André E. Punt View author

publications You can also search for this author inPubMed Google Scholar * Dongming Lin View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS

X.J.C. and F.H. designed the study, acquired data by performing the majority of laboratory experiments and drafted the manuscript; K.Z. acquired data by performing and interpreting some

experiments; A.E.P. reviewed and re-edited the manuscript; D.M.L. conceptualized the study, supervised the whole work and interpreted all the data. All authors finally approved the paper in

the present form. All authors contributed to the writing of the manuscript. CORRESPONDING AUTHOR Correspondence to Dongming Lin. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare

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permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Chen, X., Han, F., Zhu, K. _et al._ The breeding strategy of female jumbo squid _Dosidicus gigas_: energy acquisition and allocation. _Sci

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