| Animal personality,that is a prevalent trait,has been boardly defined as interindividual differences that remain consistent over time and/or contexts.Animal personalities are divided into five behavioral axes:boldness,exploration,activity,aggressiveness,and sociability.One of the commonly focused dimensions of personality is the shyness-boldness continuum.As far as fish are concerned,personality not only affects feeding,reproduction,and migration and other behaviors,but also affects physiological performance such as metabolism and immunity,as well as cognitive ability,morphology,etc.,and ultimately affecs the growth,survival and reproduction of fish.In recent years,personality research has become the basis and core of animal behavioral ecology research,and has also become a hot spot in fish behavioral ecology research.This study systematically studied the effects of personality on swimming performance and feeding performance of juvenile Siberian sturgeon(total length:15.48 ± 1.80 cm,weight:13.13±3.82g)by using the theories,methods and means of fish behavioral ecology.The results of the study not only help enrich the theory of sturgeon behavioral ecology,but also contribute to the scientific formulation of sturgeon aquaculture management measures and protection strategies.The main findings are as follows:(1)The swimming performance of shy juvenile Siberian sturgeon were better,testing evolutionary biology trade-off theory.We found that shy individuals(44.37 ± 9.99 BL/s)had stronger stable swimming performance than bold individuals(30.78 ± 11.01 BL/s).The shy individuals(26%)spent less time countercurrent forward than the bold individuals(41%,p<0.05);and the shy individuals(48%)spent more time proportion of countercurrent stationary of relative to ground than the bold ones(19%);the proportion of time of shy individuals(6%)of float downstream was three times that of the bold juvenile sturgeon(2%).On the whole,shy juvenile sturgeons had significantly stronger swimming performance than bold individuals,which verified the evolutionary biology theory that advantages in some traits of animals were formed at the cost of disadvantages in other traits.(2)The shy juvenile Siberian sturgeon were more resilient after exercise fatigue,which may be a main reason for their stronger swimming performance.The external behavior showed that the swimming fatigue recovery ability of shy individuals(R=104%)was stronger than that of bold individuals(R=95%).The intrinsic physiological performance showed that during the 24h physiological recovery period,the glucose concentration(3.97 ± 1.20 mmol/L>3.53 ± 0.86mmol/L)of shy individuals rised faster than that of bold individuals,the lactate scavenging ability(5.38 ± 2.61mmol/L>4.68 ± 2.58 mmol/L)of shy individuals was stronger than that of bold individuals,and the total protein concentration(29.64 ± 8.82 mmol/L>20.54 ± 10.34 mmol/L)of shy individuals was always higher than that of bold individuals.It may be due to the fact that shy individuals tend to use more flexible avoidance strategies when faced with "stress",thereby showing higher energy utilization efficiency(such as feeding)in daily life,and high levels of energy reserves can be preferentially used for physiological recovery.(3)The shy juvenile Siberian sturgeon were more streamlined,which may be another reason for their stronger swimming performance.The results of geometric morphometric measurements showed that the caudal fin,caudal peduncle,pectoral fin and head of fish with different personalities were significantly different.Compared with bold individuals,shy individuals had smaller caudal regions(long caudal peduncle,high caudal peduncle,upper caudal lobe,lower caudal lobe),while head regions(head height,thick snout,long snout),body height,body length larger(p<0.05).This result and the traditional morphometric analysis found that the morphological differences of Siberian sturgeon juveniles with different personalities are mainly manifested in that the head height/body length,snout length/body length,origin of anal fin origin of belly of caudal fin/body length of the shy individuals were larger than those of the bold individuals,head length/body length,Length of pectoral fin/body length,dorsal fin anterior distance/body length,dorsal fin high length/body length,Anal fin anterior distance/body length,caudal fin upper lobe length/body length,End of dorsal fin to origin of back of caudal fin/body length were smaller than that of the bold individual(p<0.05).The relatively large head and relatively small tail of shy individuals may make the body shape more streamlined,which can minimize the loss of recoil energy and enhance stable swimming performance;the relatively small head and large tail regions of bold individuals are more conducive to generating stronger propulsion and enhancing the ability to start quickly.(4)Shy juvenile Siberian sturgeon had weaker feeding ability and faster growth,more efficient energy allocation strategy may be a main reason for their stronger growth ability.It was found that the daily food intake(2.32g ± 1.85g)and total food intake(459.47g)of bold individuals were significantly higher than those of shy individuals(2.18g ± 1.84g;433.35g),respectively;their food conversion rate(7.16%)and food intake rate(0.16%)were also significantly higher than those of shy individuals(5.11%;0.13%).After the experiment,shy individuals had higher weight-specific growth rate(3.0%)and growth efficiency(19.9%)than bold individuals(2.8%;14.8%),respectively.According to the energy trade-off strategy,since bold individuals were more exploratory,aggressive,and dominant,resulting in large energy consumption,only a small part of the energy converted from food was used for weight gain.Therefore,a more efficient energy allocation strategy may lead to greater growth in shy individuals.(5)The shy juvenile Siberian sturgeon had a weaker food digestion and absorption ability,and the lower digestive enzyme activity may be one of the main reasons for its weaker feeding ability.We found that shy individuals’ gastrointestinal protease activity(16.69 ±1.82 U/mgprot<18.40 ± 3.17 U/mgprot),amylase activity(0.45 ± 0.09 U/mgprot<0.52± 0.08 U/mgprot),lipase activity(216.06 ± 46.14 U/mgprot<325.21 ± 55.04 U/mgprot)lower than bold individuals;Hepatopancreas protease activity(14.51 ± 0.81 U/mgprot<15.55 ± 0.60 U/mgprot),amylase activity(0.18 ± 0.10 U/mgprot<0.44 ± 0.28 U/mgprot),lipase activity(395.08 ± 144.60 U/mgprot<421.11 ± 165.25 U/mgprot)lower than bold individuals.It showed that compared with bold individuals,shy individuals had weaker digestion and absorption ability of food.Bold individuals achieved the purpose of improving feeding ability by regulating the activity of digestive enzymes,which was a physiological compensation mechanism for its strong exploratory with high energy consumption.In addition,we also found that compared to commercial feeds,sturgeon prefered to eat natural feeds such as red worms,which increased its protease activity and amylase activity,and reduced lipase activity,but the food conversion rate of natural feeds was lower than that of commercial feeds.Based on the above research results,in the breeding process of sturgeon,it is necessary to take targeted domestication measures to improve the stable swimming performance and fatigue recovery ability of bold individuals,thereby increasing the yield;In the artificial breeding and release work,it is recommended to quickly screen out shy individuals by body size,and give priority to releasing shy juvenile sturgeons to improve field survival and population fitness. |
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