METHODOLOGY TO FISH PRODUCTION EFFICIENCY EVALUATION
DOI:10.30825/5.EJPAU.17.2018.21.2

Małgorzata Woźniak ¹, Krystyna A. Skibniewska², Janusz Guziur¹, Janusz Zakrzewski³, Jozef Szarek^4
1 Department of Fish Biology and Pisciculture, Faculty of Environmental Sciences, University of Warmia & Mazury in Olsztyn, Poland
² Chair of Foundations of Safety, Faculty of Technical Science, University of Warmia & Mazury in Olsztyn, Poland
³ Faculty of Technical Science, University of Warmia & Mazury in Olsztyn, Poland
⁴ Chair of Pathophysiology, Forensic Veterinary Medicine & Administration, Faculty of Veterinary Medicine, University of Warmia & Mazury in Olsztyn, Poland

ABSTRACT

Development of aquaculture has resulted in the need to develop a tool to assess fish production efficiency. This study proposes a method using selected attributes which can be changed and adapted in dependence on the purpose of the assessment. The attributes are also provided with an importance level, expressed in percentage terms, due to which an attribute considered by the assessors as more significant can have a stronger impact on the final results. The usefulness of the method was tested on the results obtained for production from six fish farms using three different carp breeding technologies and from six rainbow trout farms carrying out production in flowing or recirculated water. The following attributes were applied: slaughter output, content of protein and fat, fatty acids n-3/n-6 ratio and results of organoleptic analysis. Carp bred by semi-extensive technology, next, the one bred by low-intensive method, gained the best GZS value. Also, dependence of GZS value of carp to the season of netting was confirmed. Presented results did not show influence of different farming system on the GZS value of trout bred with OOH and RAS systems. It has been shown that the method can be a useful tool for selecting the optimal technology of fish production for specified environmental conditions, as well as a supervision or reporting tool for state and non-state institutions.

Key words: fish production assessment, carp, rainbow trout.

INTRODUCTION

Aquaculture is currently one of the fastest growing forms of animal production. Since the 1990’s, global aquaculture production has been increasing annually by 10%, as compared with a 2.5% increase for other forms of animal production. In 2014 half of all fish for human consumption originated from aquaculture production [16]. Frankic and Hershner [4] believe that a dynamic increase in the production volume of aquaculture is the outcome of three main factors: strong demographic growth, a decrease in the harvest rate for aquatic (mainly marine) organisms and, in particular, changes in consumer eating preferences.

One of the most important changes in consumer preferences is the approach of the consumer towards the form of fish available for sale. In Poland, only every third buyer still wants to purchase fresh fish, while the interest in processed, and in particular, gutted and smoked fish is increasing. For consumers in the European Union, including Poland, such factors as taste, dietary and health-related values, as well as environmental conditions in which those organisms were produced will become more important in determining the purchase of aquaculture products [2, 8]. The final quality of carp, and partially of trout, is significantly affected by such environmental factors as water and pond substrate quality, the character of the reservoir. For carp (earthen) ponds, the quality and type of natural food [7, 11] and/or feed quality [9], as well as sewage and water poisoning of various types, e.g. from pesticide dump [12] is also important. The meat of carp reared in Europe should be especially promoted, since its current production formula satisfies all requirements of ecological and sustainable production [1]. The problem of bones in carp meat can be eliminated by cutting [3].

To date, the evaluation of aquaculture production in Poland, both in carp and in trout ponds, has employed only a few basic rearing and production indicators, e.g. the final volume of fish harvested (i.e. yield), survival rate of a given stock, average annual gain per fish in a season, gain per pond area (kg ha^-1), gain per feeding stuff and the population growth [6]. These are basic production indicators, required not only for annual fishing reporting but also for the purpose of calculating economic efficiency (costs) of production for a given generation of fish [17]. It should be mentioned that the breeders also included in their Pond Books other, more detailed breeding indicators, on the basis of the records kept (e.g. density of fish stock per surface unit, production intensity level, feeding stuff share in the total growth of fish as well as the quality of natural feeding stuffs and granulates applied). All of these factors led to a more objective assessment of the production level obtained, which was particularly required for planning further production for subsequent years. However, Bauer and Schlott [2] quite recently demonstrated that fish producers did not show any special interest in such features of the fish sold by them as slaughter efficiency or quality of carp or trout muscle tissue.

Over the last 20 years, as a result of the introduction of free markets in Central European countries (including Poland) the production profile of Polish pond farms (and also in the Czech Republic, Hungary, the former Yugoslavia and Slovakia) has undergone significant modifications and the scope of works has been extended, largely under the influence of market competition and required profitability of fish production [5, 10]. In order to obtain a profitable market for selling the production output, fish farms were forced to carry out the preliminary processing of fish raw material (gutting, beheading, freezing, smoking, etc.). At the same time, these operations forced the breeders to ensure proven and qualified pond fish stocking, needed for the production of consumable (commodity) fish of the desired size, dietary (nutritional) qualities and taste values [6]. In this situation, the previous assessment of fishing production for a given farm had to be extended by other factors, particularly as regards commodity characteristics and raw material-dietary qualities to ensure a more objective description of the entire production profile of a given fish farm. The aim of the study was to carry out a complex assessment of the fish farm production, taking into consideration both production yield, as well as quality of the fish meat.

MATERIALS AND METHODS

The way named GZS method was invented to carry out a complex evaluation of fish farm production. The evaluation is carried out by calculating the points for parameters that are each time selected depending on the purpose of GZS usage.

For exemplifying application of the GZS method results of two research projects were chosen.

Carp project
The project entitled: The effect of the type of fish production technology and water environment quality on selected breeding and pathomorphological indicators of consumable carp (Cyprinus carpio L.) implemented within the Sectoral Operational Programme “Fishing and Fish Processing 2004–2006” was performed in 2007 to compare quality of consumable carps bred by production technologies applied in Poland: semi-extensive technology [SE], low-intensive level [LI] and highly intensive one [HI]. Results obtained during the realization of the project were published [13, 14].

Among others, slaughter output, protein and total fat content, proportion of n-3/n-6 fatty acids and consumer parameters (general assessment of the product and the assessment calculated on the basis of individual attributes from the consumer evaluation) were determined in 180 fish caught in 6 farms.

Rainbow trout project
The project entitled: Testing the technologies of trout production applied in Poland in light of Commission Regulation (CE) No. 710/2009 implemented as part of the Operational Programme “Sustainable Development of the Fisheries Sector and Coastal Fishing Areas 2007–2013” was realized in 2010–2012. Trout was caught four times in each of the three farms with an extensive production level (OOH), i.e. farms using production water only once, and in each of the three farms using closed (i.e. return water) systems (with a high degree of recirculation – RAS). Results obtained during the realization of the project were published [15].

Among others, slaughter output, protein and total fat content, proportion of n-3/n-6 fatty acids and consumer parameters (general assessment of the product and the assessment calculated on the basis of individual attributes from the consumer evaluation) were determined in 960 fish caught in 6 farms.

Application of GZS method to carp and rainbow trout assessment
The above mentioned attributes were used for creating a table serving as the basis for carrying out the production assessment (Tab. 1 and 2). Attributes included only those features that depended on the fish breeding technology, with omission of features that were identical for all examined fish farms (i.e. water or ash content or contamination with heavy metals). In addition, such parameters as water (no differences in water quality was found) or feed consumption (all the trout feeds were of similar quality) were not included even though in some situations these parameters might be important for evaluation. Taking into account various significance levels of selected features in relation to the final assessment of production yield, the importance of an attribute was introduced, expressed as a percentage value.

The sum of points was calculated in the following manner (see Tab. 1 and 2):

Σ = 40% of A + 10% of B + 10% of C + 10% of D + 15% of E + 15% of F

The results were analysed statistically using Statistica 8.0 (α = 0.05) (StatSoft, Kraków, Poland). Normality of data distribution was checked with Kołmogorow-Smirnow test and Lilliefors test. Nonparametric U Mann-Whitney test was used to show significance differences among mean values.

Table 1. Assumptions for complex assessment of carp production by the GZS method

POINTS	A Slaughter output [%]	B Protein content [%]	C   Fat content [%]	D n-3/n-6 proportion	E Sensory quality calculated from attributes	F Sensory quality general note
Attribute importance	40%	10%	10%	10%	15%	15%
1	<60.9	15–15.9	0–1	1:1	0.1–2.0	0.1–2.0
2	61–61.9	16–16.9	1.1–1.59	1:1.1–1:1.9	2.1–4.0	2.1–4.0
3	62–63.9	17–17.9	1.6–2.0	1:2–1:2.9	4.1–6.0	4.1–6.0
4	64–68.9	18–18.9	2.1–2.5	1:3–1:3.9	6.1–8.0	6.1–8.0
5	>69	>19	2.6–3.2	1:4–1:4.9	8.1–10.0	8.1–10.0
4	X	X	3.3–5	1:5–1:5.9	X	X
3	X	X	5.1–7.5	1:6–1:6.9	X	X
2	X	X	7.6–9.9	1:7–1:7.9	X	X
1	X	X	10	>1:8	X	X
GZS result calculation: Σ = 40% of A + 10% of B + 10% of C + 10% of D + 15% of E + 15% of F

Table 2. Assumptions for complex assessment of trout production by the GZS method

POINTS	A Slaughter output [%]	B Protein content [%]	C   Fat content [%]	D n-3/n-6 proportion	E Sensory quality calculated from attributes	F Sensory quality general note
Attribute importance	40%	10%	10%	10%	15%	15%
1	<69.9	14.9	0–1	1:1	0.1–2.0	0.1–2.0
2	70–73.9	15–15.9	1.1–1.59	1:1.1–1:1.9	2.1–4.0	2.1–4.0
3	74–76.9	16–18.9	1.6–2.09	1:2–1:2.9	4.1–6.0	4.1–6.0
4	77–79.9	19–20.4	2.1–2.59	1:3–1:3.9	6.1–8.0	6.1–8.0
5	>80	>20.5	2.6–3.29	1:4–1:4.9	8.1–10.0	8.1–10.0
4	X	X	3.3–5.09	1:5–1:5.9	X	X
3	X	X	5.1–7.59	1:6–1:6.9	X	X
2	X	X	7.6–9.99	1:7 -1:7.9	X	X
1	X	X	>10	>1:8	X	X
GZS result calculation: Σ = 40% of A + 10% of B + 10% of C + 10% of D + 15% of E + 15% of F

RESULTS

Carp project
The individual values of GZS obtained for carp ranged from 2 to 4 and the mean ones are presented in Table 3. Significant differences has been shown for fish netted in the same farm different seasons – carp from semi-extensive and highly intensive technology gained better note in autumn. Opposite finding for low-intensive bred carp resulted from troubles of one of LI fish farms that experienced in summer environmental problems (deficit of oxygen) and significantly reduced their fish feeding. Comparison of GZS values calculated for meat of fish netted in July showed no differences between SE and LI carp and significantly lower mark for HI carp. In October GZS value for LI carp was significantly the lowest and for SE carp – the highest. Again, the GZS value for LI fish in October was lowered by production troubles in one of the LI firms.

Table 3. Results of GZS method for carp

FARM		SE	SE	LI	LI	HI	HI
Parameter	Harvest month	July	October	July	October	July	October
A – Slaughter output	[%]	62.4	64.1	62.3	61.6	59.6	63.7
	Points	3	4	3	2	1	3
B – Protein content	[%]	18.0	18.2	18.3	17.8	18.8	18.1
	Points	4	4	4	3	4	4
C – Fat content	[%]	1.50	2.38	0.56	1.32	1.58	1.92
	Points	2	4	1	2	2	3
D – n-3/n-6 proportion		1:2.5	1:5	1:2	1:3	1:2.5	1:4
	Points	3	4	3	4	3	5
E – SQ calculated from attributes	Mean	5.67	5.56	6.49	6.35	5.13	6.18
	Points	3	3	4	4	3	4
F – SQ general note	Mean	5.43	5.85	7.15	6.70	5.00	6.91
	Points	3	3	4	4	4	4
Σ – GZS results	Points	3.03a,B	3.68b,E	3.18d,B	2.68c,C	2.55e,A	3.28f,D
SE – semi-extensive  fish breeding technology LI – low-intensive  fish breeding technology HI – highly intensive fish breeding technology SQ – sensory quality a with b, c with d and e with f – statistically confirmed differences between fish netted in different months in the same farm A with B and C with D – statistically confirmed differences between fish netted in the same month in different farms

Rainbow trout project
The GZS values obtained for trout ranged from 2 to 5 and the means calculated for the studied trout breeding technologies are presented in Table 4. In all farms under examination, higher evaluation results were obtained for M-sortment fish (300–500 g) than for L-ones (500–800 g). The smaller fish was characterized by higher slaughter output and lower total fat content. There was no difference calculated for the same sortment trout bred under different technologies

Table 4. Results of GZS method for rainbow trout

FARM		OOH	OOH	RAS	RAS
Parameter		Fish size
		S	M	S	M
A – Slaughter output	[%]	77.42	73.83	78.33	72.45
	Points	4	2	4	2
B – Protein content	[%]	19.5	18.8	19.5	19.0
	Points	4	3	4	4
C – Fat content	[%]	1.5	3.0	1.6	2.5
	Points	2	5	3	4
D – n-3/n-6 proportion		1:3	1:3.5	1:2	1:2.3
	Points	4	4	3	3
E – SQ calculated from attributes	Mean	8.20	8.29	8.26	8.16
	Points	5	5	5	5
F – SQ general note	Mean	8.23	8.28	8.29	8.20
	Points	5	5	5	5
Σ – GZS results	Points	3.81b	3.50a	4.07d	3.37c
SQ – sensory quality OOH – fish breeding technology on the through-flow water RAS – fish breeding technology on recirculated water S – S-sortment fish  weighing 300 – 500g M – M-size fish weighing 500 – 800 g SQ – sensory quality a with b and c with d – statistically confirmed differences between fish of different sortment originating from the same farm

DISCUSSION

The comparisons made so far obviously concerned only individual parameters of fish: the content of individual components of fish meat, organoleptic properties, production yield, economical effect, etc. The method proposed in the study makes it possible to directly compare the production yield of fish of the same species reared with the application of various production technologies, while comparing major production and technological features. The literature of the subject does not provide any information on similar indicators which would take into account the above mentioned features at the same time (complex).

Increased consumer awareness concerning the nutritional and health-related values of fish raw material presents new challenges for producers, as well as for governmental and non-governmental institutions supervising inland and sea fishery in Poland. This concerns, in particular, the Ministry of Agriculture: the Department of Fishery and the Department of Veterinary Matters, in cooperation with the Agency for Reconstructing and Modernisation of Agriculture and the Ministry of the Environment. The regulations and standards of entities controlling the quality of fish have been strengthened.

The proposed GZS method will be also useful in the analysis of economic and marketing indicators and of economic efficiency of production of a farm. Therefore, it will constitute an element of a business plan for planning fishery investments and, particularly, in applications by fish farms for EU subsidiaries or credits [1, 16].

In the context of all these requirements, we propose a multi-factor GZS method considering both the choice of optimal technology, as well as the general characteristics of fishing production targeted at demanding customers. This has been proven in practice based on the results obtained from six Polish carp farms with three commonly-applied levels of production intensity: semi-extensive (production up to 0.6 t ha^-1), low-intensive (to 1.5 t ha^-1) and highly-intensive – over 1.5 t ha^-1, as well as from six fish farms carrying out production of rainbow trout in flowing or recirculated water.

CONCLUSIONS

The tool proposed should be of a considerable assistance for fish producers, facilitating selection of the optimal production technology, i.e. achieving maximum yield while preserving the high quality of fish raw material. The proposed method can be also used by state and non-governmental institutions for supervisory or statistical purposes. Attributes and their importance, at choice for every purpose of the GZS application, should be set in practical application. They will certainly differ depending on the species of fish, purpose of scale application as well as on production conditions. Comparison of the sum of points obtained for the studied fish farms helps to choose the farm producing the best material for selected purpose.It is possible that along with a change in consumer preferences, previously established assumptions might also be subject to change.

Acknowledgements

The research was financed by the projects: The effect of the type of fish production technology and water environment quality on selected breeding and pathomorphological indicators of consumable carp (Cyprinus carpio L.) implemented within the Sectoral Operational Programme “Fishing and Fish Processing 2004–2006” and Testing the technologies of trout production applied in Poland in light of Commission Regulation (CE) No. 710/2009 currently implemented as part of the Operational Programme “Sustainable Development of the Fisheries Sector and Coastal Fishing Areas 2007–2013”.

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13. Skibniewska K.A., Zakrzewski J., Kłobukowski J., Białowąs  H., Mickowska B., Guziur J., Walczak Z., Szarek J., 2013. Nutritional value of the protein of consumer carp Cyprinus carpio L. Czech Journal of Food Sciences, 31(4), 313–317.
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Accepted for print: 4.06.2018

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Małgorzata Woźniak
Department of Fish Biology and Pisciculture, Faculty of Environmental Sciences, University of Warmia & Mazury in Olsztyn, Poland
Phone: +48 89 524 51 25
10-719 Olsztyn
Poland
email: mawoz@uwm.edu.pl

Krystyna A. Skibniewska
Chair of Foundations of Safety, Faculty of Technical Science, University of Warmia & Mazury in Olsztyn, Poland
Phone: +48 89 524 56 11
Heweliusza 10
10-719 Olsztyn
Poland
email: kas@uwm.edu.pl

Janusz Guziur
Department of Fish Biology and Pisciculture, Faculty of Environmental Sciences, University of Warmia & Mazury in Olsztyn, Poland
Phone: +48 89 534 37 62
10-719 Olsztyn
Poland
email: jguziur@uwm.edu.pl

Janusz Zakrzewski
Faculty of Technical Science, University of Warmia & Mazury in Olsztyn, Poland
†

Jozef Szarek
Chair of Pathophysiology, Forensic Veterinary Medicine & Administration, Faculty of Veterinary Medicine, University of Warmia & Mazury in Olsztyn, Poland
Phone: +48 89 523 32 52
Oczapowskiego 13
10-718 Olsztyn
Poland
email: szarek@uwm.edu.pl

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