Raising Cuttlefish Studies

DWhatley

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EFFECTS OF INCREASED VOLUME AND TANK BOTTOM AREAS ON CUTTLEFISH (SEPIA OFFICINALIS, L.) REPRODUCTION BEHAVIOUR
Gavan M. Cooke, Juan C. Capaz, José Pedro Andrade, António V. Sykes 2016 (EAS40 article)

[DWhatley] Data from this study is still being analysed.

Introduction

The common European cuttlefish (Sepia officinalis) is the most used cuttlefish in research and is becoming an increasingly important aquaculture species due to its fast growth rates, adaptability to artificial food and other features (Sykes et al., 2011). Control of reproductive function in captivity is essential for the sustainability of commercial aquaculture production. It relies on species specific biological and physiological knowledge and culture conditions, which will ultimately influence animal welfare (Conte 2004). Sykes et al., (2014) recently reviewed the state of the art of S. officinalis culture and both him and Villanueva et al., (2014) have identified control over reproduction as a bottleneck in cuttlefish/cephalopods culture development.

In nature, cuttlefish are social only for reproduction, producing complex intraspecific visual displays (Hanlon et al., 1999) and form short-term female-male pair associations (Boal, 1997). Males use visual displays to probably establish size-based dominance hierarchies, where large males mate more frequently (Adamo & Hanlon, 1996; Boal, 1997). During copulation, males display sperm removal behaviour (Hanlon et al., 1999) suggesting last sperm precedence which manifests itself in mate guarding after copulation. S. officinalis is a semelparous species and this implies a different brood stock management that used for most finfish. Until now, it has been a common practice to use cultured broodstocks to obtain animals for the subsequent generations (Sykes et al., 2006). Such closed-cycle practice with captive breeders may have led to reproductive isolation from wild populations and a resultant loss of genetic variability due to the low effective breeding population size and inbreeding. We need to address this issue, by determining the effective number of breeders contributing for reproduction in an integrative way, by using behavioural analysis.

Although a number of studies to date have investigated best rearing conditions (e.g. Sykes et al, 2011) with increase in growth rates and fecundity the goal, few studies have focused solely on welfare in light of the change in legislation (but see Tonkins et al., 2015, Cooke and Tonkins, 2015). The tanks in which breeding adults are kept can have a great effect on their behaviour and ultimately welfare. Cuttlefish are epibenthic (Hanlon and Messenger, 1996) on hatching but spend at least some of their adult lives floating in the water column, possibly looking for prey and also mates. Being semelparous sexually mature individuals go through an intense breeding phase where males vigorously and aggressively compete females and females are often harassed into copulation. Given this knowledge of their life history some shapes of tanks are likely to be better than others in terms of promoting welfare. Here, we performed the first cuttlefish "big brother" and followed a large number of cuttlefish from juvenile stage right through adulthood until the onset of senescence. We believe that the different bottom areas/tank volumes will contribute differently to social behaviour within.
 

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Transcriptome Sequencing and De Novo Assembly of Golden Cuttlefish Sepia esculenta Hoyle
Changlin Liu,Fazhen Zhao,Jingping Yan,Chunsheng Liu,Siwei Liu andSiqing Chen 2016 (International Journal of Molecular Science - full article)
Abstract
:
Golden cuttlefish Sepia esculenta Hoyle is an economically important cephalopod species. However, artificial hatching is currently challenged by low survival rate of larvae due to abnormal embryonic development. Dissecting the genetic foundation and regulatory mechanisms in embryonic development requires genomic background knowledge. Therefore, we carried out a transcriptome sequencing on Sepia embryos and larvae via mRNA-Seq. 32,597,241 raw reads were filtered and assembled into 98,615 unigenes (N50 length at 911 bp) which were annotated in NR database, GO and KEGG databases respectively. Digital gene expression analysis was carried out on cleavage stage embryos, healthy larvae and malformed larvae. Unigenes functioning in cell proliferation exhibited higher transcriptional levels at cleavage stage while those related to animal disease and organ development showed increased transcription in malformed larvae. Homologs of key genes in regulatory pathways related to early development of animals were identified in Sepia. Most of them exhibit higher transcriptional levels in cleavage stage than larvae, suggesting their potential roles in embryonic development of Sepia. The de novo assembly of Sepia transcriptome is fundamental genetic background for further exploration in Sepia research. Our demonstration on the transcriptional variations of genes in three developmental stages will provide new perspectives in understanding the molecular mechanisms in early embryonic development of cuttlefish.
 

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EFFECTS OF INCREASED VOLUME AND TANK BOTTOM AREAS ON CUTTLEFISH (Sepia officinalis, L.) REPRODUCTION PERFORMANCE
António V. Sykes, Juan C. Capaz, Daniel Hernández-Brooke, Safia Balvet, Ana T. Couto, Alexandra Alves, José Pedro Andrade

Introduction

Cephalopods are gaining momentum as an alternate group for aquaculture species diversification, not only because they are a good food source (highly appreciated in some worldwide markets) but they also have the potential to quickly reach a market size. Sykes et al. (2014) recently reviewed the state of the art of Sepia officinalis culture and both him and Villanueva et al. (2014) have identified control over reproduction as a bottleneck in cuttlefish/cephalopods culture development. According to Sykes et al. (2013), the existing protocol for cuttlefish reproduction in captivity does not allow replication of results and this is probably due to not accounting for given variables, which probably have importance in increasing reproduction performance. Those are sex ratio, available space and the sexual behavior displayed when given tanks are used, which will have influence on parental contribution to offspring and population management to avoid genetic erosion and inbreeding in captive conditions. The objective of this experiment was to test the effect of tanks with different increasing volume and bottom areas on cuttlefish reproduction performance.

Material and Methods

A total of 192 juvenile cuttlefish with a mean wet weight (MWW) of 32.7±4.0g were used. These were placed in different tanks: three 3000L (3.24m2 area; B's), three 9000L (7.07m2 area; K's), and two 9000L (6.67m2 area; Q's). Each replicate/tank was set with 24 juvenile cuttlefish (which corresponded to densities of 7, 3 and 4 cuttlefish.m-2, respectively for B's, K's and Q's tanks) and a sex ratio of 2♀:1♂. All cuttlefish were weighed, every 15 days, until the start of reproduction. Data collected was used to calculate: Mean Wet Weight (MWW); Mean Absolute Instantaneous Growth Rate (MAIGR; %BW.d-1); Total Absolute Mortality (TAM); Mean Cumulative Mortality (MCM; %); Biomass (B; g); Mean Biomass Relative Increase index (B%; % BW.d-1). Additional data was collected regarding cuttlefish reproduction and used to calculate: Duration of Reproduction Stage (DRS; days); Fecundity (F; eggs); Total Egg Biomass (EB; g); Mean Individual Fecundity (IF; eggs.female-1); Mean, Maximum and Minimum egg weight (MEW; MaxIEW; MinIEWg); Mean female and male weight (MW♀; MW♂; g); Dorsal mantle length (DML); Eviscerated, gonads and digestive gland wet weight; Gonadossomatic Index (GI); Digestive Gland Index (DGI); Number of Egg Batches (Ba; n); Number of Eggs per Batch (EBa; eggs.batch-1); Viable and non-viable eggs (n); Egg viability (%); and Mean Hatchling Weight (MHW; g). Sex ratios were verified at the end of the experiment. Viable and non-viable eggs were sorted by external morphology and colour, according to table 11.2 and fig. 11.3 of Sykes et al. (2014). Egg Viability of was determined randomly in 100 viable eggs from a tank batch placed 2.6L hatching tanks (22.0cmx14.5cmx8.0cm) of a semi-open seawater system (250L). This procedure was performed three times in each tank, depending on egg availability for each tank.

Results and Discussion

Cuttlefish displayed a life span of 289 days, which was much larger than that recorded previously by Sykes et al. (2006), in consecutive generations, and Sykes et al. (2013). The main differences found at the end of the growth stage was as higher mortality in the B tanks.

Despite one the of B tanks contributed with only 369 eggs, the 8 tanks generated a total of 123751 eggs (in 85 postures), which is not only the highest number of eggs ever obtained at CCMar's facilities but also a number of eggs that may meet the requirements of a small scale cuttlefish commercial hatchery facility. This is even more significant if we consider that these results were obtained with an F5 generation of captive cuttlefish breeders and that the experimental tanks were placed outside the premises.

There were two K tanks reaching a production of approximately 24000 eggs/tank and individual fecundities of 1500 eggs/female. It is interesting that both K and Q tanks presented not only high values of total fecundity but also that these were fairly consistent between replicates, when compared with B tanks. In the present experiment, a lower number of batches but a higher number of eggs per batch was verified, being these much more consistent in K tanks. The non-viable egg percentage increased, when compared with the Sykes et al. (2013) paper, but this was probably due to the use of a F5 generation, while the previous used a F1.
 

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Acute and Chronic Effects of Ammonia on Juvenile Cuttlefish, Sepia pharaoni
Rui-Bing Peng, Peng-Shuai Wang, Ke-Xin Le, Yuang wang, Qing-Xi Han, Xia-Min Jiang 2017 (World Aquaculture Society subscription)
Abstract
The aim of this study was to provide a reference value for the safe regulation and control of ammonia nitrogen in the aquaculture of Sepia pharaonis. The effects of acute and chronic toxicity of ammonia on the cuttlefish, S. pharaonis, were tested experimentally using juvenile S. pharaonis. The results showed that the half-lethal concentration (LC50 ) values of ammonia nitrogen in juvenile S. pharaoniswith a body weight of 6.52 ± 0. 23 g at 24, 48, 72, and 96 h were 31.72, 25.77, 23.33, and 18.33 mg/L, respectively, and the corresponding un-ionized ammonia nitrogen (UIA-N) concentrations were 1.66, 1.35, 1.22, and 0.96 mg/L, respectively. Compared with the control, the survival rate, specific growth rate, and feed intake of juvenile S. pharaonis declined significantly, and the feed conversion ratio and hepatosomatic index increased significantly at 56 d after exposure to >1 mg/L ammonia nitrogen. Juvenile S. pharaonis should be maintained at a concentration of ammonia nitrogen of no more than 1 mg/L (UIA-N is 0.056 mg/L) in culture, and removing harmful nitrogenous wastes from the seawater is critical in maintaining cuttlefish culture.
 

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