Globally, aquaculture contributes to sustainable food and nutritional stability. However, stress conditions constitute a major threat affecting farmed-fish welfare and fish farms’ performances. In this regard, the present study was aimed at measuring and comparing in-situ (offshore) the physiological stress responses caused by recurrent sampling operations for length–weight measurement. Studied fish were European sea bass Dicentrarchus labrax sub-adults and adults reared in intensive farming conditions in M’diq Bay, on the Moroccan Mediterranean coast. The physiological stress response was evaluated by measuring blood biomarkers, including cortisol, glucose, lactate, total cholesterol and total proteins levels, and hematocrit percentage. The hypercortisolemia, hyperglycemia, hyperlactatemia and hypoproteinemia detected in the post-sampling state in both age groups of D. labrax indicated stress tendencies and a high sensitivity to aquaculture practice-related stress factors, with major and minor responses detected in the same age and same stress conditions. It is also interesting to note that the fish age and the time-course of the sampling operation had a statistically significant effect in terms of the physiological response (with p < 0.01 and p < 0.001, respectively). In conclusion, the present study showed that sea bass subjected to various stressful situations in intensive farming conditions displayed a physiological stress response specific to its age, to the individual status, as well as to the duration of stressor.

The present study aimed at studying ecological interaction between a fish farm cages located in M’diq bay, in western Moroccan Mediterranean coast, and its local environment. It was carried out in 2013 and 2016 through seabed analysis in terms of organic matter and some nutrients parameters such as Nitrogen and Phosphorus, as well as through monitoring macro-fauna assemblages. The results showed recorded values relatively stable in three years’ interval and have a well-integrated fish farming activity within its ecosystem. Sediment was sandy to sandy shelly types and macro-benthic fauna were composed of six groups, Gastropods, Bivalves, Scaphopoda, Amphipods, Nematoda and Polychaeta. Organic matter and Total Organic Carbon were respectively less than 3.2% and 1.87% and very low comparing with others Mediterranean fish farms sites. Estimation of Nitrogen, Phosphorus and Carbon potential releases of M’diq fish farm gave low data related to its production capacity not exceeding 200 tons by year. Influenced with open sea location and high current state, dispersion pattern of these fish farm discharges seemed to play a key role in keeping lower values. ANOVA analysis showed no significant difference between studied parameters in the five sampling stations comparing with the reference station both on geographical and temporal levels (seasons and years).

Cost production and profitability analysis was performed for a marine fish farm, located in M’diq Bay, in Morocco. Currently, it is the alone farm in operation on Moroccan Mediterranean cost while three others had been ceased their activity. Created in 1998, it has experienced three main periods during its history, start-up period, followed by a crisis period followed by a recovery period on which the present study has been focused on. Production costs analysis has shown financial results yielding a very low profitability (0.24%). Two main constraints were found to be relevant, one environmental related to the weak local annual seawater temperature profile (18°C in average, 14-21°C in range) and the other technical related to feed and fingerlings management. The use of SGR and TGC tools, based on real growing and production data, have allowed to establish suitable start-up date for annual batches. Feed and fingerlings constraints have analysed in order to contribute in production costs improvement. Results showed that total costs could be reduced and profitability improved following pertinent inputs management optimization, marketing strategies improvement and production plan adjustment. Support measures provided by public powers offer suitable opportunity to improve farm’s financial results.

The present study assesses the carbon footprint of the only operating marine fish farm in Morocco. Five years of data were used to assess its carbon footprint, following ISO/TS 14067 standard, the PAS 2050 and the IPCC 2006 guidelines. The obtained carbon footprint ranged from 2.34 to 2.85 kg CO2e/kg. The emission value for 2017 is 38% lower than the highest value. Fish feed contributes most to the carbon footprint of the farm. Based on PAS 2050, the inshore cage farming product ranks in the same category as dairy products. Furthermore, the comparison showed that it is almost 67% lower than the carbon footprint of other protein production. This study evaluates some scenarios for reducing the carbon footprint of the fish farm, which can be a basis for further studies.

The present study purposed to quantify and compare in‐situ the primary and secondary physiological stress responses, related to the operation of floating net‐cages changing, in both sub‐adults (523 days post hatching) and adults (916 dph) European sea bass Dicentrarchus labrax, under intensive farming conditions in the Moroccan M'diq Bay. Levels of cortisol, glucose, total cholesterol, total protein and lactate, as well as the percentage of hematocrit were measured before and after stress. The results showed significantly elevated levels of cortisol and blood glucose in both age groups, while total cholesterol and protein levels were unaffected. In fact, blood lactate was significantly reduced in sub‐adults, while in adults this parameter was not affected by the operation. However, the hematocrit percentages measured after the operation were significantly higher than those found before the operation in both groups of fish, which is linked to the increased rate of oxygen renewal by the new net cages and the lower water temperature inside the cages. With regard to the age‐specific response during this essential operation ‐ before and after the operation ‐ plasma cortisol, blood glucose and lactate concentrations, as well as plasma total protein levels, were significantly higher in sub‐adults than in adults. It is concluded that aquaculture practices such as changing the aquaculture net‐cage could have repercussions in terms of the classic physiological responses to stress in D. labrax.This article is protected by copyright. All rights reserved.