Abstract:

Data for this study was compromised of empirical data and the nutritional composition of mahi-mahi (Coryphaena hippurus) spawns over a 10-week period. Empirical data consisted of egg morphometries and the larval survival of these spawns over the time course of this study. Larval survival was quantified using the survival activity indices (SAIs) for larval survival at 1 dph and 3 dph as metric to assess egg quality. The larval SAIs were correlated to the nutritional composition of eggs over the time course of this study.

Suggested Citation:

Steven Kloeblen. 2017. Egg Quality and larval performance of captive mahi-mahi (Coryphaena hippurus) spawns over time. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7WD3XM0

Publications:

Kloeblen, S., Stieglitz, J. D., Suarez, J. A., Grosell, M., & Benetti, D. D. (2017). Characterizing egg quality and larval performance from captive mahi-mahi Coryphaena hippurus (Linnaeus, 1758) spawns over time. Aquaculture Research. doi:10.1111/are.13459

Purpose:

The dataset was developed to assess egg quality of wild-caught mahi-mahi broodstock and to examine the survival of larvae from these subsequent spawns over the time course that the broodstock are in captivity. This was done by collecting spawns over a 10-week period from when the broodstock were initially captured. Two spawns were collected weekly for this study based on the availability of the broodstock spawning. For each spawn, a subsample of eggs was assessed at which stage of development: early cleavage, morula, later embryonic stages, etc. in order that the eggs from time periods of the study were at the same stage of development since the morphometries and possible nutritional composition of the eggs can change during embryonic development. A subsample of 90 eggs from each spawn collected and the egg diameters and egg oil globule diameters were measured using Leica CME microscope equipped with an ocular micrometer at 40 X magnification. An additional subsample of eggs (n = 40) was collected for each spawn and stocked in a replicated PELEC system. Daily mortality post hatch was measured until the larvae had died due starvation. A survival activity index (SAI) (see Materials and methods) was performed using this data for larval survival at 1 day post hatch (dph) and 3 dph. Water Quality parameters (temperature, dissolved oxygen, salinity, pH, and total ammonia (NH4+)) were collected at the day of the spawn in the Maturation spawning tank and at the initial and final days of each Larval SAI in the PELEC systems. For each spawn, collected the eggs were weighed (g) and were sent off for nutritional analysis (Vitamin A, E, and C, a complete amino acid profile, fatty acid profile, and phospholipid profile). Total volume of eggs and percentage of floating/sinking was measured in a volumetric beaker. Egg morphometries, larval SAI were correlated to the changes in the nutritional composition of eggs over the time course over to assess the egg quality of wild mahi-mahi broodstock to see if the captive diet had an effect ultimately on larval survival. Additionally, gonads from wild mahi and broodstock that had been in captivity for this study were sent off nutritional analysis to compare the differences in the nutritional composition of gonads for the duration of captivity.

Data Parameters and Units:

In this study, the egg mophometries: egg diameter and egg oil globule diameter were measured using Leica CME microscope. The units for these parameters were measured in micrometers (µm). The trial days indicate at which day the trial was performed starting at 1 day (1 day post the capture of the broodstock) to 71 days later. The number of broodstock refers to the number of broodstock in the spawning tank during each trial period, these changed over time with removal of excess males, deaths, or culls. The volume of the spawn was measured in the volumetric beaker and amount of the floating and sinking eggs were measured. The volume of eggs was measured in milliliters (ml). The stage of development indicates the embryonic stage of development at which the eggs were flash frozen for nutritional analysis. The amount of sample was the quantity of egg sample that was flash frozen for nutritional analysis. This was measured in grams (g). The larval survival data was performed in the replicated PELEC systems (n = 4) for each spawn collected. Each beaker in the PELEC system had 40 eggs supplied in it (See excel sheet). Daily survival starting day 3 (post hatch) was measured until all the larvae had died to starvation (represented by the number 0). Days in larval survival data sheet refers the number of days in each larval survival trial until all the larval had died due to starvation. Beakers refer to each individual cone in the PELEC system with corresponding numbers below referring to the number of eggs and hatched larvae that were alive on each day. Day 57 of this study, beaker 2 in the replicated was removed from the study due to tear in the silicone tubing causing the eggs drain out of the PELEC system and therefore crash. Water parameters were measured in temperature (measured in degrees Celsius (º C)), dissolved oxygen (measured in milligrams per liter (mg/L)), salinity (measured in parts per thousand (ppt)), and total ammonia (NH4+) (measured in milligrams per liter (mg/L)). In the initial PELEC system water parameter results total ammonia analysis was not performed and is indicated by NA (not applicable). In the final PELEC system water parameter results, total ammonia analysis was measured using indophenol blue method (see materials and methods) and the results were indicated in micromoles per liter (µmol/L) and was converted into milligrams per liter (mg/L). Negative results indicate that the results were too close to the generated standard curve (indicating very low values for total ammonia). In the nutritional analysis, days post capture indicated the day in which the spawn was collected. Gonad sample 1 was indicated by “wild” which refers to pooled gonads from wild caught mahi-mahi that were euthanized during the broodstock capture trip while gonad sample 2 was indicated by “captive” which were pooled gonads from wild-caught broodstock that were held during the duration of this study. Sample description indicates which sample it was ordinally. Test name indicates the test was performed on each sample. For some of the test names it has AOAC in the parameter name, this refers to Association of Official Analytical Chemists which is an association which publishes standardized, chemical analysis methods. For the fatty acid tests, AOCS refers to American Oil Chemists Society which provides standardized, chemical analysis methods particularly for fats and oils. Parameter name refers to the particular analysis for each particular test performed. For the fatty acids, the chemical formula indicated by Cn1:n2 where C refers to the carbon in the fatty acid chain, n1 refers number of carbons in the fatty acid chain, and n2 refers to the number of double bonds in the fatty acid chain. Unit value refers to the numeric value of each test performed (“<” means that the analysis was below the sensitivity of analysis). Units refers to the particular unit of measurement used for each analysis where IU/100 g means international unit per 100 grams of sample, mg/100 g means milligram per 100 grams of sample, and “ %” means percent of sample. For the phospholipid analysis, the unit value is parts per million (ppm). “ <” for the unit value means that the value was below the sensitivity of the analysis.

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